Speed Up Firefox: Use QuickJava To Block Flash, Silverlight And More

Justin Pot 23-12-2013

Is your browsing too slow? Block the stuff that’s bogging you down. QuickJava is a simple Firefox extension that gives you the ability to temporarily turn off browser plugins.


Things like Flash, Silverlight and Java are great at extending what the web can do, but they can also make it unbearable. Flash ads use processing power, burn up battery reserves and play sounds – all without asking you for permission. The performance hit from browser plugins like Flash is significant – which is the reason mobile device manufacturers refuse to include them.

QuickJava [No Longer Available] is one of our favorite Firefox addons The Best Firefox Addons Firefox is famous for its extensions. But which addons are the most useful? Here are the ones we think are best, what they do, and where you can find them. Read More , because of how easy it makes turning off these resource-hungry plugins for desktop users. You can even take things to an extreme, turning of CSS and images entirely (not recommended). Here’s how it works.

Using QuickJava [No Longer Available]

Install QuickJava, then restart Firefox. When you do you’ll see two new things. The first is a button up top:


Click this to quickly turn off your “favorite” plugins, by default Javascript, Java and Flash. If you’ve got the Firefox Statusbar enabled, you’ll also see these icons below:



Clicking the buttons can individually block, from left:

  • Javascript (JS)
  • Java (J)
  • Flash (F)
  • Silverlight (SL)
  • Cookies (C)
  • Images (I)
  • Animated Images/GIFs (A)
  • Style/CSS (CS)

Hover over any box if you need a reminder about what’s what.

You can change what shows up where easily in the extension’s settings. Right-click the icon, then click “Options”:



Several settings can be edited manually, but feel free to ignore this if you don’t understand it.

Blocking: A Mixed Blessing

If you block things, sites will break. More than a few sites rely on cookies for logging in, and turning off CSS will quickly make the modern web unusable. Gmail will run like crap, if at all, if you turn off JavaScript.

This doesn’t mean you shouldn’t use this extension, but it does mean you need to think before you just turn everything off. Be selective about what you block: I recommend leaving it at Java, Flash and Silverlight, unless you really know what you’re doing.


Happily, blocking those three things is straightforward. Here’s what a flash item looks like with Flash blocked:


Simple, right? Sadly there’s no one-click way to re-enable flash for just one item, unlike Chrome’s built-in option (more on that later). But you can turn flash back on with just a couple of clicks, retracing the steps outlined above.

If you’re stuck using Airport, or otherwise pathetically slow WiFi, I actually recommend turning off images along with Flash and Silverlight. Firefox is insanely fast when you do:



It’s quick to toggle, so play around. Find settings you like for different circumstances, and let us know what works for you in the comments below.

What About Chrome?

QuickJava is a Firefox exclusive, but that doesn’t mean Chrome users are out of luck. That browser offers, built in, a “Click to Play” setting for browser plugins:


You’ll find this in Chrome’s settings. You’ll need to click “Show Advanced Settings”, then “Content Settings”. This works mostly like QuickJava, but is actually better in one key way: you can re-enable Flash for individual items. This means you could, say, watch a video on a news site without also enabling the flash ad on that same page. I wish QuickJava worked more like this.


Like I said, blocking Flash and Silverlight by default can seriously increase your browser’s, and potentially your computer’s, performance. Turning off other things can break things, but is also kind of fun to play with. I recommend you give this a spin if you’re looking to get just a little more out of your browser.

Want to do even more? Erez outlined other tips to help you keep Firefox from becoming unbearably slow How To Keep Firefox From Getting Unbearably Slow I don’t like Firefox. I think it is a monolithic, huge, heavy browser, and its XPI-based architecture feels slow and dated. Firefox is more flexible than other browsers like Chrome but it also gradually slows... Read More , and Tina outlined how to make Firefox start faster How To Make Your Firefox Browser Start Up Faster Read More , so check those out if you want even better performance. Do you have other tips for speeding up Firefox? Please share them below!

Image credits: Red Panda Yawning by Neil McIntosh via Flickr

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  1. kittycats4netneutrality
    February 6, 2015 at 8:43 pm

    ad block plus is the best ad blocking addon for firefox!

  2. manfred
    January 22, 2014 at 4:28 pm

    Install "Firemin" and your memory consumptions is gone!!

  3. Simon
    December 26, 2013 at 3:30 pm

    Yes, I don't know why MakeUseOf didn't mention that. I guess it's a sponsored post for QuickJava.
    How to enable Click to Play in Firefox: First, make sure "plugins.click_to_play" is set to true in about:config (should be the default in Firefox 26). Then, go to Addons (Ctrl + Shift + A) -> Plugins - and choose "Ask To Activate" from the dropdown menu next to the plugin. You will then be asked to activate that plugin each time a site needs it, and you can activate it temporarily or always for this site (for example
    How to block images: open a new tab, type about:config, press Enter, confirm warning, search for permissions.default.image, double click to set it to false.
    Simple, right?

    • Tina S
      December 27, 2013 at 10:56 pm

      Simon, this is not a sponsored post; we disclose sponsoring. This is a single app review; Quick Java is one of our best Firefox addons.

      It's unfortunate that both the author and the editor of this post (me) missed Firefox's native feature. Thank you for pointing it out!

      It might in fact be time to remove the app from the Best Of list.

    • Doug G.
      January 23, 2014 at 3:17 pm


      When developing the latest version of QuickJava I had played with the new "ClickToPlay" state, but couldn't get it to work properly because I hadn't found the about:config option yet. When a user emailed me last December asking about support for this functionality I dug in a bit more and found it. The functionality is there, you just have to turn it on! Since there seems to be further interest I have posted a 'how to' on the support page of the site.

      Also, QJ does not pay for any reviews, posts or any other form of content. Any feedback is purely from the community (the way it should be!).

      Tina, Obviously I would like to convince you not to remove QJ from your Best Of list, my ego appreciates it! Haha, that aside I hope you can see the future development path and value that QJ brings outside of the ClickToPlay realm for users and developers alike in regards to JavaScript, Images, Cookies, ect.

      Justin, Thank you for such a gracious review and simple how-to writeup. As noted it is not available for Chrome because when I was asked about porting it Chrome did not give their addons enough power to control any of the things QuickJava does. They have since added their click to play functionality and enhanced the API to support toggling JavaScript, but there is an addon that already handles that (written by somebody else):

  4. Anomaly
    December 23, 2013 at 4:06 pm

    Fire has this function built into it just like Google Chrome does.