diff --git a/src/applications/search/ferret/PhabricatorFerretEngine.php b/src/applications/search/ferret/PhabricatorFerretEngine.php
index 7d1d03a8b1..7cd06ae549 100644
--- a/src/applications/search/ferret/PhabricatorFerretEngine.php
+++ b/src/applications/search/ferret/PhabricatorFerretEngine.php
@@ -1,284 +1,298 @@
 <?php
 
 abstract class PhabricatorFerretEngine extends Phobject {
 
   abstract public function getApplicationName();
   abstract public function getScopeName();
   abstract public function newSearchEngine();
 
   public function getDefaultFunctionKey() {
     return 'all';
   }
 
   public function getObjectTypeRelevance() {
     return 1000;
   }
 
   public function getFieldForFunction($function) {
     $function = phutil_utf8_strtolower($function);
 
     $map = $this->getFunctionMap();
     if (!isset($map[$function])) {
       throw new PhutilSearchQueryCompilerSyntaxException(
         pht(
           'Unknown search function "%s". Supported functions are: %s.',
           $function,
           implode(', ', array_keys($map))));
     }
 
     return $map[$function]['field'];
   }
 
   public function getAllFunctionFields() {
     $map = $this->getFunctionMap();
 
     $fields = array();
     foreach ($map as $key => $spec) {
       $fields[] = $spec['field'];
     }
 
     return $fields;
   }
 
   protected function getFunctionMap() {
     return array(
       'all' => array(
         'field' => PhabricatorSearchDocumentFieldType::FIELD_ALL,
         'aliases' => array(
           'any',
         ),
       ),
       'title' => array(
         'field' => PhabricatorSearchDocumentFieldType::FIELD_TITLE,
         'aliases' => array(),
       ),
       'body' => array(
         'field' => PhabricatorSearchDocumentFieldType::FIELD_BODY,
         'aliases' => array(),
       ),
       'core' => array(
         'field' => PhabricatorSearchDocumentFieldType::FIELD_CORE,
         'aliases' => array(),
       ),
       'comment' => array(
         'field' => PhabricatorSearchDocumentFieldType::FIELD_COMMENT,
         'aliases' => array(
           'comments',
         ),
       ),
     );
   }
 
   public function newStemmer() {
     return new PhutilSearchStemmer();
   }
 
   public function tokenizeString($value) {
     $value = trim($value, ' ');
     $value = preg_split('/\s+/u', $value);
     return $value;
   }
 
   public function getTermNgramsFromString($string) {
     return $this->getNgramsFromString($string, true);
   }
 
   public function getSubstringNgramsFromString($string) {
     return $this->getNgramsFromString($string, false);
   }
 
   private function getNgramsFromString($value, $as_term) {
     $value = phutil_utf8_strtolower($value);
     $tokens = $this->tokenizeString($value);
 
     // First, extract unique tokens from the string. This reduces the number
     // of `phutil_utf8v()` calls we need to make if we are indexing a large
     // corpus with redundant terms.
     $unique_tokens = array();
     foreach ($tokens as $token) {
       if ($as_term) {
         $token = ' '.$token.' ';
       }
 
       $unique_tokens[$token] = true;
     }
 
     $ngrams = array();
     foreach ($unique_tokens as $token => $ignored) {
       $token_v = phutil_utf8v($token);
-      $len = (count($token_v) - 2);
-      for ($ii = 0; $ii < $len; $ii++) {
-        $ngram = array_slice($token_v, $ii, 3);
-        $ngram = implode('', $ngram);
+      $length = count($token_v);
+
+      // NOTE: We're being somewhat clever here to micro-optimize performance,
+      // especially for very long strings. See PHI87.
+
+      $token_l = array();
+      for ($ii = 0; $ii < $length; $ii++) {
+        $token_l[$ii] = strlen($token_v[$ii]);
+      }
+
+      $ngram_count = $length - 2;
+      $cursor = 0;
+      for ($ii = 0; $ii < $ngram_count; $ii++) {
+        $ngram_l = $token_l[$ii] + $token_l[$ii + 1] + $token_l[$ii + 2];
+
+        $ngram = substr($token, $cursor, $ngram_l);
         $ngrams[$ngram] = $ngram;
+
+        $cursor += $token_l[$ii];
       }
     }
 
     ksort($ngrams);
 
     return array_keys($ngrams);
   }
 
   public function newTermsCorpus($raw_corpus) {
     $term_corpus = strtr(
       $raw_corpus,
       array(
         '!' => ' ',
         '"' => ' ',
         '#' => ' ',
         '$' => ' ',
         '%' => ' ',
         '&' => ' ',
         '(' => ' ',
         ')' => ' ',
         '*' => ' ',
         '+' => ' ',
         ',' => ' ',
         '-' => ' ',
         '/' => ' ',
         ':' => ' ',
         ';' => ' ',
         '<' => ' ',
         '=' => ' ',
         '>' => ' ',
         '?' => ' ',
         '@' => ' ',
         '[' => ' ',
         '\\' => ' ',
         ']' => ' ',
         '^' => ' ',
         '`' => ' ',
         '{' => ' ',
         '|' => ' ',
         '}' => ' ',
         '~' => ' ',
         '.' => ' ',
         '_' => ' ',
         "\n" => ' ',
         "\r" => ' ',
         "\t" => ' ',
       ));
 
     // NOTE: Single quotes divide terms only if they're at a word boundary.
     // In contractions, like "whom'st've", the entire word is a single term.
     $term_corpus = preg_replace('/(^| )[\']+/', ' ', $term_corpus);
     $term_corpus = preg_replace('/[\']+( |$)/', ' ', $term_corpus);
 
     $term_corpus = preg_replace('/\s+/u', ' ', $term_corpus);
     $term_corpus = trim($term_corpus, ' ');
 
     if (strlen($term_corpus)) {
       $term_corpus = ' '.$term_corpus.' ';
     }
 
     return $term_corpus;
   }
 
 /* -(  Schema  )------------------------------------------------------------- */
 
   public function getDocumentTableName() {
     $application = $this->getApplicationName();
     $scope = $this->getScopeName();
 
     return "{$application}_{$scope}_fdocument";
   }
 
   public function getDocumentSchemaColumns() {
     return array(
       'id' => 'auto',
       'objectPHID' => 'phid',
       'isClosed' => 'bool',
       'authorPHID' => 'phid?',
       'ownerPHID' => 'phid?',
       'epochCreated' => 'epoch',
       'epochModified' => 'epoch',
     );
   }
 
   public function getDocumentSchemaKeys() {
     return array(
       'PRIMARY' => array(
         'columns' => array('id'),
         'unique' => true,
       ),
       'key_object' => array(
         'columns' => array('objectPHID'),
         'unique' => true,
       ),
       'key_author' => array(
         'columns' => array('authorPHID'),
       ),
       'key_owner' => array(
         'columns' => array('ownerPHID'),
       ),
       'key_created' => array(
         'columns' => array('epochCreated'),
       ),
       'key_modified' => array(
         'columns' => array('epochModified'),
       ),
     );
   }
 
   public function getFieldTableName() {
     $application = $this->getApplicationName();
     $scope = $this->getScopeName();
 
     return "{$application}_{$scope}_ffield";
   }
 
   public function getFieldSchemaColumns() {
     return array(
       'id' => 'auto',
       'documentID' => 'uint32',
       'fieldKey' => 'text4',
       'rawCorpus' => 'sort',
       'termCorpus' => 'sort',
       'normalCorpus' => 'sort',
     );
   }
 
   public function getFieldSchemaKeys() {
     return array(
       'PRIMARY' => array(
         'columns' => array('id'),
         'unique' => true,
       ),
       'key_documentfield' => array(
         'columns' => array('documentID', 'fieldKey'),
         'unique' => true,
       ),
     );
   }
 
   public function getNgramsTableName() {
     $application = $this->getApplicationName();
     $scope = $this->getScopeName();
 
     return "{$application}_{$scope}_fngrams";
   }
 
   public function getNgramsSchemaColumns() {
     return array(
       'id' => 'auto',
       'documentID' => 'uint32',
       'ngram' => 'char3',
     );
   }
 
   public function getNgramsSchemaKeys() {
     return array(
       'PRIMARY' => array(
         'columns' => array('id'),
         'unique' => true,
       ),
       'key_ngram' => array(
         'columns' => array('ngram', 'documentID'),
       ),
       'key_object' => array(
         'columns' => array('documentID'),
       ),
     );
   }
 
 }
diff --git a/src/applications/search/ferret/__tests__/PhabricatorFerretEngineTestCase.php b/src/applications/search/ferret/__tests__/PhabricatorFerretEngineTestCase.php
index a8690f1d8b..ea65a559ff 100644
--- a/src/applications/search/ferret/__tests__/PhabricatorFerretEngineTestCase.php
+++ b/src/applications/search/ferret/__tests__/PhabricatorFerretEngineTestCase.php
@@ -1,27 +1,57 @@
 <?php
 
 final class PhabricatorFerretEngineTestCase
   extends PhabricatorTestCase {
 
   public function testTermsCorpus() {
     $map = array(
       'Hear ye, hear ye!' => ' Hear ye hear ye ',
       "Thou whom'st've art worthy." => " Thou whom'st've art worthy ",
       'Guaranteed to contain "food".' => ' Guaranteed to contain food ',
       'http://example.org/path/to/file.jpg' =>
         ' http example org path to file jpg ',
     );
 
     $engine = new ManiphestTaskFerretEngine();
 
     foreach ($map as $input => $expect) {
       $actual = $engine->newTermsCorpus($input);
 
       $this->assertEqual(
         $expect,
         $actual,
         pht('Terms corpus for: %s', $input));
     }
   }
 
+  public function testTermNgramExtraction() {
+    $snowman = "\xE2\x98\x83";
+
+    $map = array(
+      'a' => array(' a '),
+      'ab' => array(' ab', 'ab '),
+      'abcdef' => array(' ab', 'abc', 'bcd', 'cde', 'def', 'ef '),
+      "{$snowman}" => array(" {$snowman} "),
+      "x{$snowman}y" => array(
+        " x{$snowman}",
+        "x{$snowman}y",
+        "{$snowman}y ",
+      ),
+      "{$snowman}{$snowman}" => array(
+        " {$snowman}{$snowman}",
+        "{$snowman}{$snowman} ",
+      ),
+    );
+
+    $engine = new ManiphestTaskFerretEngine();
+
+    foreach ($map as $input => $expect) {
+      $actual = $engine->getTermNgramsFromString($input);
+      $this->assertEqual(
+        $actual,
+        $expect,
+        pht('Term ngrams for: %s.', $input));
+    }
+  }
+
 }