diff --git a/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php b/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php
index 0ffc280edf..45cf8bcd9d 100644
--- a/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php
+++ b/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php
@@ -1,110 +1,110 @@
 <?php
 
 /**
  * @group console
  */
 final class DarkConsoleXHProfPlugin extends DarkConsolePlugin {
 
   protected $profileFilePHID;
 
   public function getName() {
     return 'XHProf';
   }
 
   public function getColor() {
     $data = $this->getData();
     if ($data['profileFilePHID']) {
       return '#ff00ff';
     }
     return null;
   }
 
   public function getDescription() {
     return 'Provides detailed PHP profiling information through XHProf.';
   }
 
   public function generateData() {
     return array(
       'profileFilePHID' => $this->profileFilePHID,
       'profileURI' => (string)$this
         ->getRequestURI()
         ->alter('__profile__', 'page'),
     );
   }
 
   public function getXHProfRunID() {
     return $this->profileFilePHID;
   }
 
   public function renderPanel() {
     $data = $this->getData();
 
     $run = $data['profileFilePHID'];
     $profile_uri = $data['profileURI'];
 
     if (!DarkConsoleXHProfPluginAPI::isProfilerAvailable()) {
       $href = PhabricatorEnv::getDoclink('article/Installation_Guide.html');
       $install_guide = phutil_tag(
         'a',
         array(
           'href' => $href,
           'class' => 'bright-link',
         ),
         'Installation Guide');
       return hsprintf(
         '<div class="dark-console-no-content">'.
           'The "xhprof" PHP extension is not available. Install xhprof '.
           'to enable the XHProf console plugin. You can find instructions in '.
           'the %s.'.
         '</div>',
         $install_guide);
     }
 
     $result = array();
 
     $header = phutil_tag(
       'div',
       array('class' => 'dark-console-panel-header'),
       array(
         phutil_tag(
           'a',
           array(
             'href'  => $profile_uri,
             'class' => $run ? 'disabled button' : 'green button',
           ),
           pht('Profile Page')),
         phutil_tag('h1', array(), pht('XHProf Profiler')),
       ));
     $result[] = $header;
 
     if ($run) {
       $result[] = phutil_tag(
         'a',
         array(
           'href' => "/xhprof/profile/$run/",
           'class' => 'bright-link',
           'style' => 'float: right; margin: 1em 2em 0 0; font-weight: bold;',
           'target' => '_blank',
         ),
         pht('Profile Permalink'));
-      $result = phutil_tag(
+      $result[] = phutil_tag(
         'iframe',
         array('src' => "/xhprof/profile/$run/?frame=true"));
     } else {
       $result[] = phutil_tag(
         'div',
         array('class' => 'dark-console-no-content'),
         pht(
           'Profiling was not enabled for this page. Use the button above '.
           'to enable it.'));
     }
 
     return phutil_implode_html("\n", $result);
   }
 
 
   public function willShutdown() {
     $this->profileFilePHID = DarkConsoleXHProfPluginAPI::getProfileFilePHID();
   }
 
 }
diff --git a/src/infrastructure/markup/PhabricatorMarkupEngine.php b/src/infrastructure/markup/PhabricatorMarkupEngine.php
index 884798b322..764ca6f79a 100644
--- a/src/infrastructure/markup/PhabricatorMarkupEngine.php
+++ b/src/infrastructure/markup/PhabricatorMarkupEngine.php
@@ -1,576 +1,583 @@
 <?php
 
 /**
  * Manages markup engine selection, configuration, application, caching and
  * pipelining.
  *
  * @{class:PhabricatorMarkupEngine} can be used to render objects which
  * implement @{interface:PhabricatorMarkupInterface} in a batched, cache-aware
  * way. For example, if you have a list of comments written in remarkup (and
  * the objects implement the correct interface) you can render them by first
  * building an engine and adding the fields with @{method:addObject}.
  *
  *   $field  = 'field:body'; // Field you want to render. Each object exposes
  *                           // one or more fields of markup.
  *
  *   $engine = new PhabricatorMarkupEngine();
  *   foreach ($comments as $comment) {
  *     $engine->addObject($comment, $field);
  *   }
  *
  * Now, call @{method:process} to perform the actual cache/rendering
  * step. This is a heavyweight call which does batched data access and
  * transforms the markup into output.
  *
  *   $engine->process();
  *
  * Finally, do something with the results:
  *
  *   $results = array();
  *   foreach ($comments as $comment) {
  *     $results[] = $engine->getOutput($comment, $field);
  *   }
  *
  * If you have a single object to render, you can use the convenience method
  * @{method:renderOneObject}.
  *
  * @task markup Markup Pipeline
  * @task engine Engine Construction
  */
 final class PhabricatorMarkupEngine {
 
   private $objects = array();
   private $viewer;
   private $version = 8;
 
 
 /* -(  Markup Pipeline  )---------------------------------------------------- */
 
 
   /**
    * Convenience method for pushing a single object through the markup
    * pipeline.
    *
    * @param PhabricatorMarkupInterface  The object to render.
    * @param string                      The field to render.
    * @param PhabricatorUser             User viewing the markup.
    * @return string                     Marked up output.
    * @task markup
    */
   public static function renderOneObject(
     PhabricatorMarkupInterface $object,
     $field,
     PhabricatorUser $viewer) {
     return id(new PhabricatorMarkupEngine())
       ->setViewer($viewer)
       ->addObject($object, $field)
       ->process()
       ->getOutput($object, $field);
   }
 
 
   /**
    * Queue an object for markup generation when @{method:process} is
    * called. You can retrieve the output later with @{method:getOutput}.
    *
    * @param PhabricatorMarkupInterface  The object to render.
    * @param string                      The field to render.
    * @return this
    * @task markup
    */
   public function addObject(PhabricatorMarkupInterface $object, $field) {
     $key = $this->getMarkupFieldKey($object, $field);
     $this->objects[$key] = array(
       'object' => $object,
       'field'  => $field,
     );
 
     return $this;
   }
 
 
   /**
    * Process objects queued with @{method:addObject}. You can then retrieve
    * the output with @{method:getOutput}.
    *
    * @return this
    * @task markup
    */
   public function process() {
     $keys = array();
     foreach ($this->objects as $key => $info) {
       if (!isset($info['markup'])) {
         $keys[] = $key;
       }
     }
 
     if (!$keys) {
       return;
     }
 
     $objects = array_select_keys($this->objects, $keys);
 
     // Build all the markup engines. We need an engine for each field whether
     // we have a cache or not, since we still need to postprocess the cache.
     $engines = array();
     foreach ($objects as $key => $info) {
       $engines[$key] = $info['object']->newMarkupEngine($info['field']);
       $engines[$key]->setConfig('viewer', $this->viewer);
     }
 
     // Load or build the preprocessor caches.
     $blocks = $this->loadPreprocessorCaches($engines, $objects);
     $blocks = mpull($blocks, 'getCacheData');
 
     $this->engineCaches = $blocks;
 
     // Finalize the output.
     foreach ($objects as $key => $info) {
       $engine = $engines[$key];
       $field = $info['field'];
       $object = $info['object'];
 
       $output = $engine->postprocessText($blocks[$key]);
       $output = $object->didMarkupText($field, $output, $engine);
       $this->objects[$key]['output'] = $output;
     }
 
     return $this;
   }
 
 
   /**
    * Get the output of markup processing for a field queued with
    * @{method:addObject}. Before you can call this method, you must call
    * @{method:process}.
    *
    * @param PhabricatorMarkupInterface  The object to retrieve.
    * @param string                      The field to retrieve.
    * @return string                     Processed output.
    * @task markup
    */
   public function getOutput(PhabricatorMarkupInterface $object, $field) {
     $key = $this->getMarkupFieldKey($object, $field);
     $this->requireKeyProcessed($key);
 
     return $this->objects[$key]['output'];
   }
 
 
   /**
    * Retrieve engine metadata for a given field.
    *
    * @param PhabricatorMarkupInterface  The object to retrieve.
    * @param string                      The field to retrieve.
    * @param string                      The engine metadata field to retrieve.
    * @param wild                        Optional default value.
    * @task markup
    */
   public function getEngineMetadata(
     PhabricatorMarkupInterface $object,
     $field,
     $metadata_key,
     $default = null) {
 
     $key = $this->getMarkupFieldKey($object, $field);
     $this->requireKeyProcessed($key);
 
     return idx($this->engineCaches[$key]['metadata'], $metadata_key, $default);
   }
 
 
   /**
    * @task markup
    */
   private function requireKeyProcessed($key) {
     if (empty($this->objects[$key])) {
       throw new Exception(
         "Call addObject() before using results (key = '{$key}').");
     }
 
     if (!isset($this->objects[$key]['output'])) {
       throw new Exception(
         "Call process() before using results.");
     }
   }
 
 
   /**
    * @task markup
    */
   private function getMarkupFieldKey(
     PhabricatorMarkupInterface $object,
     $field) {
 
-    $custom = array_merge(
-      self::loadCustomInlineRules(),
-      self::loadCustomBlockRules());
-
-    $custom = mpull($custom, 'getRuleVersion', null);
-    ksort($custom);
-    $custom = PhabricatorHash::digestForIndex(serialize($custom));
+    static $custom;
+    if ($custom === null) {
+      $custom = array_merge(
+        self::loadCustomInlineRules(),
+        self::loadCustomBlockRules());
+
+      $custom = mpull($custom, 'getRuleVersion', null);
+      ksort($custom);
+      $custom = PhabricatorHash::digestForIndex(serialize($custom));
+    }
 
     return $object->getMarkupFieldKey($field).'@'.$this->version.'@'.$custom;
   }
 
 
   /**
    * @task markup
    */
   private function loadPreprocessorCaches(array $engines, array $objects) {
     $blocks = array();
 
     $use_cache = array();
     foreach ($objects as $key => $info) {
       if ($info['object']->shouldUseMarkupCache($info['field'])) {
         $use_cache[$key] = true;
       }
     }
 
     if ($use_cache) {
       try {
         $blocks = id(new PhabricatorMarkupCache())->loadAllWhere(
           'cacheKey IN (%Ls)',
           array_keys($use_cache));
         $blocks = mpull($blocks, null, 'getCacheKey');
       } catch (Exception $ex) {
         phlog($ex);
       }
     }
 
     foreach ($objects as $key => $info) {
       if (isset($blocks[$key])) {
         // If we already have a preprocessing cache, we don't need to rebuild
         // it.
         continue;
       }
 
       $text = $info['object']->getMarkupText($info['field']);
       $data = $engines[$key]->preprocessText($text);
 
       // NOTE: This is just debugging information to help sort out cache issues.
       // If one machine is misconfigured and poisoning caches you can use this
       // field to hunt it down.
 
       $metadata = array(
         'host' => php_uname('n'),
       );
 
       $blocks[$key] = id(new PhabricatorMarkupCache())
         ->setCacheKey($key)
         ->setCacheData($data)
         ->setMetadata($metadata);
 
       if (isset($use_cache[$key])) {
         // This is just filling a cache and always safe, even on a read pathway.
         $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
           $blocks[$key]->replace();
         unset($unguarded);
       }
     }
 
     return $blocks;
   }
 
 
   /**
    * Set the viewing user. Used to implement object permissions.
    *
    * @param PhabricatorUser The viewing user.
    * @return this
    * @task markup
    */
   public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
 
 /* -(  Engine Construction  )------------------------------------------------ */
 
 
 
   /**
    * @task engine
    */
   public static function newManiphestMarkupEngine() {
     return self::newMarkupEngine(array(
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newPhrictionMarkupEngine() {
     return self::newMarkupEngine(array(
       'header.generate-toc' => true,
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newPhameMarkupEngine() {
     return self::newMarkupEngine(array(
       'macros' => false,
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newFeedMarkupEngine() {
     return self::newMarkupEngine(
       array(
         'macros'      => false,
         'youtube'     => false,
 
       ));
   }
 
 
   /**
    * @task engine
    */
   public static function newDifferentialMarkupEngine(array $options = array()) {
     return self::newMarkupEngine(array(
       'differential.diff' => idx($options, 'differential.diff'),
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newDiffusionMarkupEngine(array $options = array()) {
     return self::newMarkupEngine(array(
     ));
   }
 
   /**
    * @task engine
    */
   public static function getEngine($ruleset = 'default') {
     static $engines = array();
     if (isset($engines[$ruleset])) {
       return $engines[$ruleset];
     }
 
     $engine = null;
     switch ($ruleset) {
       case 'default':
         $engine = self::newMarkupEngine(array());
         break;
+      case 'nolinebreaks':
+        $engine = self::newMarkupEngine(array());
+        $engine->setConfig('preserve-linebreaks', false);
+        break;
       case 'diviner':
         $engine = self::newMarkupEngine(array());
         $engine->setConfig('preserve-linebreaks', false);
   //    $engine->setConfig('diviner.renderer', new DivinerDefaultRenderer());
         $engine->setConfig('header.generate-toc', true);
         break;
       default:
         throw new Exception("Unknown engine ruleset: {$ruleset}!");
     }
 
     $engines[$ruleset] = $engine;
     return $engine;
   }
 
   /**
    * @task engine
    */
   private static function getMarkupEngineDefaultConfiguration() {
     return array(
       'pygments'      => PhabricatorEnv::getEnvConfig('pygments.enabled'),
       'youtube'       => PhabricatorEnv::getEnvConfig(
         'remarkup.enable-embedded-youtube'),
       'differential.diff' => null,
       'header.generate-toc' => false,
       'macros'        => true,
       'uri.allowed-protocols' => PhabricatorEnv::getEnvConfig(
         'uri.allowed-protocols'),
       'syntax-highlighter.engine' => PhabricatorEnv::getEnvConfig(
         'syntax-highlighter.engine'),
       'preserve-linebreaks' => true,
     );
   }
 
 
   /**
    * @task engine
    */
   public static function newMarkupEngine(array $options) {
 
     $options += self::getMarkupEngineDefaultConfiguration();
 
     $engine = new PhutilRemarkupEngine();
 
     $engine->setConfig('preserve-linebreaks', $options['preserve-linebreaks']);
     $engine->setConfig('pygments.enabled', $options['pygments']);
     $engine->setConfig(
       'uri.allowed-protocols',
       $options['uri.allowed-protocols']);
     $engine->setConfig('differential.diff', $options['differential.diff']);
     $engine->setConfig('header.generate-toc', $options['header.generate-toc']);
     $engine->setConfig(
       'syntax-highlighter.engine',
       $options['syntax-highlighter.engine']);
 
     $rules = array();
     $rules[] = new PhutilRemarkupRuleEscapeRemarkup();
     $rules[] = new PhutilRemarkupRuleMonospace();
 
 
     $rules[] = new PhutilRemarkupRuleDocumentLink();
 
     if ($options['youtube']) {
       $rules[] = new PhabricatorRemarkupRuleYoutube();
     }
 
     $applications = PhabricatorApplication::getAllInstalledApplications();
     foreach ($applications as $application) {
       foreach ($application->getRemarkupRules() as $rule) {
         $rules[] = $rule;
       }
     }
 
     $rules[] = new PhutilRemarkupRuleHyperlink();
 
     if ($options['macros']) {
       $rules[] = new PhabricatorRemarkupRuleImageMacro();
       $rules[] = new PhabricatorRemarkupRuleMeme();
     }
 
     $rules[] = new PhutilRemarkupRuleBold();
     $rules[] = new PhutilRemarkupRuleItalic();
     $rules[] = new PhutilRemarkupRuleDel();
 
     foreach (self::loadCustomInlineRules() as $rule) {
       $rules[] = $rule;
     }
 
     $blocks = array();
     $blocks[] = new PhutilRemarkupEngineRemarkupQuotesBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupLiteralBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupHeaderBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupHorizontalRuleBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupListBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupCodeBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupNoteBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupTableBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupSimpleTableBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupInterpreterRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupDefaultBlockRule();
 
     foreach (self::loadCustomBlockRules() as $rule) {
       $blocks[] = $rule;
     }
 
     foreach ($blocks as $block) {
       $block->setMarkupRules($rules);
     }
 
     $engine->setBlockRules($blocks);
 
     return $engine;
   }
 
   public static function extractPHIDsFromMentions(array $content_blocks) {
     $mentions = array();
 
     $engine = self::newDifferentialMarkupEngine();
     $engine->setConfig('viewer', PhabricatorUser::getOmnipotentUser());
 
     foreach ($content_blocks as $content_block) {
       $engine->markupText($content_block);
       $phids = $engine->getTextMetadata(
         PhabricatorRemarkupRuleMention::KEY_MENTIONED,
         array());
       $mentions += $phids;
     }
 
     return $mentions;
   }
 
   public static function extractFilePHIDsFromEmbeddedFiles(
     array $content_blocks) {
     $files = array();
 
     $engine = self::newDifferentialMarkupEngine();
     $engine->setConfig('viewer', PhabricatorUser::getOmnipotentUser());
 
     foreach ($content_blocks as $content_block) {
       $engine->markupText($content_block);
       $ids = $engine->getTextMetadata(
         PhabricatorRemarkupRuleEmbedFile::KEY_EMBED_FILE_PHIDS,
         array());
       $files += $ids;
     }
 
     return $files;
   }
 
   /**
    * Produce a corpus summary, in a way that shortens the underlying text
    * without truncating it somewhere awkward.
    *
    * TODO: We could do a better job of this.
    *
    * @param string  Remarkup corpus to summarize.
    * @return string Summarized corpus.
    */
   public static function summarize($corpus) {
 
     // Major goals here are:
     //  - Don't split in the middle of a character (utf-8).
     //  - Don't split in the middle of, e.g., **bold** text, since
     //    we end up with hanging '**' in the summary.
     //  - Try not to pick an image macro, header, embedded file, etc.
     //  - Hopefully don't return too much text. We don't explicitly limit
     //    this right now.
 
     $blocks = preg_split("/\n *\n\s*/", trim($corpus));
 
     $best = null;
     foreach ($blocks as $block) {
       // This is a test for normal spaces in the block, i.e. a heuristic to
       // distinguish standard paragraphs from things like image macros. It may
       // not work well for non-latin text. We prefer to summarize with a
       // paragraph of normal words over an image macro, if possible.
       $has_space = preg_match('/\w\s\w/', $block);
 
       // This is a test to find embedded images and headers. We prefer to
       // summarize with a normal paragraph over a header or an embedded object,
       // if possible.
       $has_embed = preg_match('/^[{=]/', $block);
 
       if ($has_space && !$has_embed) {
         // This seems like a good summary, so return it.
         return $block;
       }
 
       if (!$best) {
         // This is the first block we found; if everything is garbage just
         // use the first block.
         $best = $block;
       }
     }
 
     return $best;
   }
 
   private static function loadCustomInlineRules() {
     return id(new PhutilSymbolLoader())
       ->setAncestorClass('PhabricatorRemarkupCustomInlineRule')
       ->loadObjects();
   }
 
   private static function loadCustomBlockRules() {
     return id(new PhutilSymbolLoader())
       ->setAncestorClass('PhabricatorRemarkupCustomBlockRule')
       ->loadObjects();
   }
 
 }
diff --git a/src/infrastructure/markup/PhabricatorMarkupOneOff.php b/src/infrastructure/markup/PhabricatorMarkupOneOff.php
index f0f213fc12..ec112e5c00 100644
--- a/src/infrastructure/markup/PhabricatorMarkupOneOff.php
+++ b/src/infrastructure/markup/PhabricatorMarkupOneOff.php
@@ -1,67 +1,68 @@
 <?php
 
 /**
  * Concrete object for accessing the markup engine with arbitrary blobs of
  * text, like form instructions. Usage:
  *
  *   $output = PhabricatorMarkupEngine::renderOneObject(
  *     id(new PhabricatorMarkupOneOff())->setContent($some_content),
  *     'default',
  *     $viewer);
  *
  * This is less efficient than batching rendering, but appropriate for small
  * amounts of one-off text in form instructions.
  */
 final class PhabricatorMarkupOneOff implements PhabricatorMarkupInterface {
 
   private $content;
   private $preserveLinebreaks;
 
   public function setPreserveLinebreaks($preserve_linebreaks) {
     $this->preserveLinebreaks = $preserve_linebreaks;
     return $this;
   }
 
   public function setContent($content) {
     $this->content = $content;
     return $this;
   }
 
   public function getContent() {
     return $this->content;
   }
 
   public function getMarkupFieldKey($field) {
     return PhabricatorHash::digestForIndex($this->getContent()).':oneoff';
   }
 
   public function newMarkupEngine($field) {
-    return PhabricatorMarkupEngine::newMarkupEngine(
-      array(
-        'preserve-linebreaks' => $this->preserveLinebreaks,
-      ));
+    if ($this->preserveLinebreaks) {
+      return PhabricatorMarkupEngine::getEngine();
+    } else {
+      return PhabricatorMarkupEngine::getEngine('nolinebreaks');
+    }
   }
 
   public function getMarkupText($field) {
     return $this->getContent();
   }
 
   public function didMarkupText(
     $field,
     $output,
     PhutilMarkupEngine $engine) {
 
     require_celerity_resource('phabricator-remarkup-css');
     return phutil_tag(
       'div',
       array(
         'class' => 'phabricator-remarkup',
       ),
       $output);
   }
 
   public function shouldUseMarkupCache($field) {
     return true;
   }
 
 }