--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -1301,21 +1301,16 @@ pref("pdfjs.disabled", false);
 // Used by pdf.js to know the first time firefox is run with it installed so it
 // can become the default pdf viewer.
 pref("pdfjs.firstRun", true);
 // The values of preferredAction and alwaysAskBeforeHandling before pdf.js
 // became the default.
 pref("pdfjs.previousHandler.preferredAction", 0);
 pref("pdfjs.previousHandler.alwaysAskBeforeHandling", false);
 
-// The maximum amount of decoded image data we'll willingly keep around (we
-// might keep around more than this, but we'll try to get down to this value).
-// (This is intentionally on the high side; see bug 746055.)
-pref("image.mem.max_decoded_image_kb", 256000);
-
 // Is the sidebar positioned ahead of the content browser
 pref("sidebar.position_start", true);
 
 // Block insecure active content on https pages
 pref("security.mixed_content.block_active_content", true);
 
 // Show degraded UI for http pages with password fields.
 pref("security.insecure_password.ui.enabled", true);

--- a/mobile/android/chrome/content/MemoryObserver.js
+++ b/mobile/android/chrome/content/MemoryObserver.js
@@ -36,19 +36,16 @@ var MemoryObserver = {
           tabs[i].zombify();
         }
       }
     }
 
     // Change some preferences temporarily for only this session
     let defaults = Services.prefs.getDefaultBranch(null);
 
-    // Reduce the amount of decoded image data we keep around
-    defaults.setIntPref("image.mem.max_decoded_image_kb", 0);
-
     // Stop using the bfcache
     if (!Services.prefs.getBoolPref("browser.sessionhistory.bfcacheIgnoreMemoryPressure")) {
       this._defaultMaxContentViewers = defaults.getIntPref(MAX_CONTENT_VIEWERS_PREF);
       defaults.setIntPref(MAX_CONTENT_VIEWERS_PREF, 0);
     }
   },
 
   handleEnoughMemory: function() {