How can I solve display glitches and poor performance with ATI fglrx driver on my ThinkPad X100e?

Solution 1:

Just do sudo aticonfig --initial after installing the the HD3200 driver and you're done.

Solution 2:

To revert back to the open source drivers it should be a simple matter of disabling the Proprietary Drivers in the Additional Drivers application. After that you will need to restart (or at least logout and log back in).

Also take a look here for a bunch of xorg.conf options to tweak the FGLRX drivers. If I were you I'd setup a xorg.conf which would a) allow you to easily swap between the closed source and open source drivers and b) allow you to tweak the drivers more. To do so take a look at the Ubuntu wiki