- The best way to try different PCSX2 configurations and examine how they affect speed, is to use the Presets at the bottom of the configuration window. Preset 1 is slowest but most compatible, preset 4 is generally both safe and relatively fast, and preset 6 will many times give fake FPS read (i.e. FPS is high, but the game actually runs slow).

- Watch the values which the presets affect while moving the presets slider (especially at the "Speed hacks" tab), and you can also change them manually while the presets are disabled.

- When not using presets, It's important to make sure that "Automatic game fixes" is checked at the system menu (done automatically when using presets). It automatically applies various specific configuration values to many games, to improve/correct emulation of these games.

- Using superVU for VU0 and/or VU1 (at the VUs configuration tab) might increase speed slightly for some games, but superVU is generally less compatible than the newer (and default) microVU. The presets don't change between mVU/sVU, so you might want to try it manually. Also FYI, superVU is no longer being actively developed or improved.

- Clamping Mode (for VUs/EE/IOP): you might get a slight speed increase when changing to 'None', but it might also negatively affect compatibility. Recommended: Leave at 'Normal'.

- Vsync: can make games run slower. Recommended: leave disabled.

- Frame skipping: many times breaks visual display. Recommended: leave at 'Disabled'.

- Game fixes: they fix various issues with emulation and may break other things. Recommended: leave all of them disabled (they would still be applied automatically when needed if the 'Automatic game fixes' is checked). The only exception is the 'EE timing hack', which might improve speed slightly for some games, and might badly break other games, or just have no effect at all.

- Other settings, which were not mentioned above are best left at their defaults.