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browser.newtab.preload does not work



in the release notes of Firefox 24 there is a changed-object called: Performance improvements on New Tab Page loads. Following the link brings me to a feature-object on Bugzilla telling me the new-tab page preloads the webpages.

This preloading doesn't work. The images won't show up (except the ones in cache) and checking the activity in Fiddler tells me there is no preloading (see: http://i.imgur.com/PZ51172.jpg)

To be honest. The preloading did work once when I just installed the update. Afterwards it failed every single time.

Chosen solution

The Webpages aren't being pre-loaded, only the new tab page is reloaded so that when you open it, you no longer get a connecting Icon and it loads instantly. The web pages on the new tab page aren't pre-loaded at all.

Read this answer in context 10

Additional System Details

Installed Plug-ins

  • Shockwave Flash 11.8 r800
  • Next Generation Java Plug-in 10.40.2 for Mozilla browsers
  • Adobe PDF Plug-In For Firefox and Netscape 10.1.8
  • 5.1.20513.0
  • Nokia Suite Enabler Plugin
  • Website Logon Plugin
  • A plugin to detect whether the Adobe Application Manager is installed on this machine.
  • Plugin for Wacom tablets.
  • The plug-in allows you to open and edit files using Microsoft Office applications
  • Office Authorization plug-in for NPAPI browsers


  • Firefox 24.0
  • User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:24.0) Gecko/20100101 Firefox/24.0
  • Support URL: https://support.mozilla.org/1/firefox/24.0/WINNT/nl/


  • Adblock Plus 2.3.2 ({d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d})
  • DownThemAll! 2.0.16 ({DDC359D1-844A-42a7-9AA1-88A850A938A8})
  • eID België 1.0.18 (belgiumeid@eid.belgium.be)
  • Element Hiding Helper voor Adblock Plus 1.2.3 (elemhidehelper@adblockplus.org)
  • FiddlerHook (fiddlerhook@fiddler2.com)
  • Firebug 1.12.1 (firebug@software.joehewitt.com)
  • FirePHP 0.7.4 (FirePHPExtension-Build@firephp.org)
  • Flagfox 4.2.12 ({1018e4d6-728f-4b20-ad56-37578a4de76b})
  • Greasemonkey 1.11 ({e4a8a97b-f2ed-450b-b12d-ee082ba24781})
  • OpenDownload² 3.4.3 ({210249CE-F888-11DD-B868-4CB456D89593})
  • RSS Icon In Awesombar 1.4 (rssicon@jasnapaka.com)
  • Troubleshooter 1.1a (troubleshooter@mozilla.org)
  • Web Developer 1.2.5 ({c45c406e-ab73-11d8-be73-000a95be3b12})
  • Adobe Acrobat - Create PDF 1.2 (web2pdfextension@web2pdf.adobedotcom) (Inactive)
  • Adobe Contribute Toolbar 6.1 ({01A8CA0A-4C96-465b-A49B-65C46FAD54F9}) (Inactive)


  • incrementalGCEnabled: True


  • adapterDescription: AMD Radeon HD 6520G (Microsoft Corporation - WDDM v1.20)
  • adapterDescription2:
  • adapterDeviceID: 0x9647
  • adapterDeviceID2:
  • adapterDrivers: aticfx64 aticfx64 aticfx64 aticfx32 aticfx32 aticfx32 atiumd64 atidxx64 atidxx64 atiumdag atidxx32 atidxx32 atiumdva atiumd6a atitmm64
  • adapterDrivers2:
  • adapterRAM: 512
  • adapterRAM2:
  • adapterVendorID: 0x1002
  • adapterVendorID2:
  • direct2DEnabled: False
  • direct2DEnabledMessage: [u'blockedDriver']
  • directWriteEnabled: False
  • directWriteVersion: 6.2.9200.16581
  • driverDate: 6-19-2012
  • driverDate2:
  • driverVersion:
  • driverVersion2:
  • info: {u'AzureCanvasBackend': u'skia', u'AzureFallbackCanvasBackend': u'cairo', u'AzureContentBackend': u'none'}
  • isGPU2Active: False
  • numAcceleratedWindows: 1
  • numTotalWindows: 1
  • webglRenderer: Google Inc. -- ANGLE (AMD Radeon HD 6520G (Microsoft Corporation - WDDM v1.20) Direct3D9Ex vs_3_0 ps_3_0)
  • windowLayerManagerRemote: False
  • windowLayerManagerType: Direct3D 9

Modified Preferences

  • browser.cache.disk.capacity: 358400
  • browser.cache.disk.smart_size.first_run: False
  • browser.cache.disk.smart_size.use_old_max: False
  • browser.cache.disk.smart_size_cached_value: 358400
  • browser.places.smartBookmarksVersion: 4
  • browser.startup.homepage: about:home
  • browser.startup.homepage_override.buildID: 20130910160258
  • browser.startup.homepage_override.mstone: 24.0
  • browser.tabs.warnOnClose: False
  • dom.mozApps.used: True
  • extensions.lastAppVersion: 24.0
  • gfx.blacklist.direct2d: 3
  • gfx.direct3d.last_used_feature_level_idx: 0
  • network.cookie.prefsMigrated: True
  • places.history.expiration.transient_current_max_pages: 104858
  • plugin.disable_full_page_plugin_for_types: application/pdf
  • plugin.importedState: True
  • plugin.state.npdeployjava: 0
  • privacy.donottrackheader.enabled: True
  • privacy.sanitize.migrateFx3Prefs: True
  • security.default_personal_cert: Select Automatically
  • security.disable_button.openCertManager: False
  • security.disable_button.openDeviceManager: False


  • User JS: No
  • Accessibility: No
Tyler Downer
  • Administrator
  • Moderator
1164 solutions 6634 answers

Chosen Solution

The Webpages aren't being pre-loaded, only the new tab page is reloaded so that when you open it, you no longer get a connecting Icon and it loads instantly. The web pages on the new tab page aren't pre-loaded at all.

  • Top 10 Contributor
  • Moderator
10739 solutions 96651 answers

Helpful Reply

Pages that send a no-store or no-cache header (Tools > Page Info > General) aren't cached and thus Firefox does not generate a thumbnail. The thumbnails on the about:newtab page are generated from the cache, so if the page is not in the cache or otherwise can't be rendered as a PNG image then you will get an empty box.
Do not use "Clear Recent History" to clear data when you close Firefox.
If there is no history then you get an about:newtab page with empty boxes.

pol098 0 solutions 3 answers

Helpful Reply

For anybody still using the Google Toolbar (while officially incompatible with Firefox it works perfectly; a minor patch is required to make it install, it originally checked for a Firefox version not beyond, I think, 4): with the Google Toolbar installed and browser.newtab.preload true, the "add tab" facility does not work since Firefox 24. Setting browser.newtab.preload false restores proper functioning. See https://support.mozilla.org/en-US/questions/967747#answer-483758