Erratic FPS with fglrx, low FPS on radeon, 7660G + 7670M laptop

[Espionage724]

My experience is mostly with Dota 2 (also applies to L4D2 and HL2:DM), but basically, I'll either have erratic FPS when using fglrx (FPS climbs to about 50 or so, then slowly drops to about 15, and then climbs back up; it's pretty consistent too so it's basically a slow stutter), or I'll have just low FPS with radeon (mainly with Dota 2, FPS stays around 20-ish; unsure of other games).

I use the 7670M in my laptop (muxless, so it's used for rendering and sends it to the 7660G, or however that works). Is this just the experience that is expected currently, or is there perhaps something I'm not setting up properly/missing?

[Dusk of Oolacile]

Sounds like CPU bottleneck. What CPU do you have?