Comment 3 for bug 1123108

I am experiencing the same issue... however:

Desktop: Core2Quad Q6600 on Radeon 2600XT (open source drivers) Ubuntu 13.04 6GB RAM/512MB VRAM
Laptop: Core2Duo T6600 on Mobility Radeon 4670 4GB RAM/1GB VRAM

On my desktop I have a 1080p monitor and a 1440x900 monitor.

I've tried 1080p monitors on my laptop, HDTV, and my secondary desktop monitor, and my laptop is profoundly faster than my desktop. I understand that it is to be expected as my laptop has a faster card and 2x the VRAM, but the difference in performance seems too much.

CPU usage is low, I think the bottleneck is how the GPU is used. Results from radeontop:
When the dash opens, Graphics Pipe usage shoots up to 92%. Just typing in the app lens (or any other lens) causes my graphics pipe usage to sustain at 80~95%, even when the only things in the dash are my text and "sorry there are no applications that match your search." Also, the unity preview animations are slow and again cause the gpu usage to skyrocket.

Furthermore, moving windows, maximize/minimize all are fast, the only slowness is with the switcher and the dash.

I hope this helps in narrowing down where the issues are :)