From what I've tested, Jak 3 is like the most speedhack-compatible game for the emulator so far. I'm running it with all speedhacks enabled (yeah, even VU cycle steal at full), and the graphics stay exactly the same, but the game is actually playable! Putting VU cycle stealing to full seems to have a huge effect on fps, as well as the other vu hacks (the rest of the options don't have as big of an effect, but still provide some boost).
System specs / emulator info if you don't believe me (

):
- Intel Core 2 Duo T6600 2.2 Ghz
- 4 GB RAM
- Ati Mobility Radeon HD 4670 XT 1 GB
- Windows 7 Home Premium 64 bit
PCSX2 v1888 public beta, March 2010 plugins package, Direct3D10 hardware mode (Gsdx SSE41 plugin) with internal res set to 1920x1080, SPU2-X plugin with 2x reverb and 5.1 expansion (doesn't matter tho).
Some fps drops in certain areas like the monk temple's main lobby, but for the most part it's fully playable even on my medium spec laptop. Graphics still look bugged at places but I guess that's a given until the emulator advances...it looks decent enough for me though. Some areas like the monk temple volcano and especially cutscenes even display fine without any texture flickering.