Well as the title says. glxinfo just says Mesa and I assume this is not the driver from AMD being loaded, as I get terrible FPS in 3D games.
Ubuntu 12.04 Mobility Radeon HD 3400 Series
You can find out which driver is in use by running the following command in a terminal:
This will give you an output similar to this one (from my Lenovo G770):
01:00.0 VGA compatible controller : Advanced Micro Devices [AMD] nee ATI Whistler [AMD Radeon HD 6600M Series] [1002:6741] Subsystem: Lenovo Device [17aa:3976] Kernel driver in use: radeon
In this case, you can see that I am using the "radeon" driver, which refers to the open source radeon drivers. If the proprietary AMD Catalyst drivers were in use, "radeon" would be replaced with "fglrx".
If you would like to install the proprietary AMD Catalyst drivers (which would certainly improve your FPS), you can do so by following the directions here. Please note that although two more recent versions of the Catalyst driver have been released since these directions were written, the RadeonHD 3400 series is no longer supported under these newer versions, so you will have to stick with 12.4. Additionally, in order for this driver to work properly with your card, you will need to be running kernel 3.2 or below and Xserver 1.11 or below (see this page for more information)
The most easy way to do that. Open "System Settings" > Details > Overview > the string "Graphics". If you see the word "Gallium" there then it means you use a free driver with 3d support. Also you can look at the output of the