diff --git a/src/aphront/response/AphrontResponse.php b/src/aphront/response/AphrontResponse.php
--- a/src/aphront/response/AphrontResponse.php
+++ b/src/aphront/response/AphrontResponse.php
@@ -54,7 +54,16 @@
 
 
   public function getContentIterator() {
-    return array($this->buildResponseString());
+    // By default, make sure responses are truly returning a string, not some
+    // kind of object that behaves like a string.
+
+    // We're going to remove the execution time limit before dumping the
+    // response into the sink, and want any rendering that's going to occur
+    // to happen BEFORE we release the limit.
+
+    return array(
+      (string)$this->buildResponseString(),
+    );
   }
 
   public function buildResponseString() {
diff --git a/src/aphront/sink/AphrontHTTPSink.php b/src/aphront/sink/AphrontHTTPSink.php
--- a/src/aphront/sink/AphrontHTTPSink.php
+++ b/src/aphront/sink/AphrontHTTPSink.php
@@ -112,6 +112,23 @@
       $response->getHTTPResponseMessage());
     $this->writeHeaders($all_headers);
 
+    // Allow clients an unlimited amount of time to download the response.
+
+    // This allows clients to perform a "slow loris" attack, where they
+    // download a large response very slowly to tie up process slots. However,
+    // concurrent connection limits and "RequestReadTimeout" already prevent
+    // this attack. We could add our own minimum download rate here if we want
+    // to make this easier to configure eventually.
+
+    // For normal page responses, we've fully rendered the page into a string
+    // already so all that's left is writing it to the client.
+
+    // For unusual responses (like large file downloads) we may still be doing
+    // some meaningful work, but in theory that work is intrinsic to streaming
+    // the response.
+
+    set_time_limit(0);
+
     $abort = false;
     foreach ($data as $block) {
       if (!$this->isWritable()) {