After I have installed Ubuntu 12.04 LTS (32 bits), Firefox 12 works fine but without hardware acceleration. Needless to say I have the latest nVidia's proprietary drivers installed and my Firefox Preferences, on "Advanced" tab, "Browsing" section, have the option "Use hardware acceleration when available" checked.

I have tried the following things before asking this question:

• Creating a boolean key "webgl.force-enabled" and set it to true on Firefox's page about:config;

• Starting a new profile like commented on thread Mozilla Firefox 12 is very slow on Ubuntu 12.04 LTS;

• I have updated my nVidia driver to version 295.53.

And none of this have worked. As you can see below in my Firefox's page about:support report, "Graphics" section shows no "GPU Accelerated Windows":

Adapter Description     NVIDIA Corporation -- GeForce GTX 460/PCIe/SSE2
Vendor ID               NVIDIA Corporation
Device ID               GeForce GTX 460/PCIe/SSE2
Driver Version          4.2.0 NVIDIA 295.53
WebGL Renderer          NVIDIA Corporation -- GeForce GTX 460/PCIe/SSE2 -- 4.2.0 NVIDIA 295.53
GPU Accelerated Windows 0
AzureBackend            skia

I use the following site to test hardware acceleration:

http://ie.microsoft.com/testdrive/Performance/FishBowl/

On Windows 7 I get 60 fps even with 1,750 fishes on browser's Full Screen Mode (1680x1050x32bit-color). On Ubuntu 12.04 LTS, same nVidia drivers (as shown in report), won't go faster than 15 fps with only 1,000 fishes.

Can anybody help me?

Best Regards,