Performance issues in a game after reinstalling - suggestions?

[Silmeria]

(The game is Vindictus, not that that matters... it runs on the Source graphics engine)

It is a laptop. Which drivers can actually affect performance, aside from graphics/bios?

1) Graphics drivers have been restored. Fairly certain they are the same version.
2) Ran bios update
3) Changed power management to "Full performance", turning off power-saving mechanisms. Strangely, I remember these settings being on power-saving mode prior to reinstalling.

Remarks
3) No SP1 installed yet because it fails to install. Could SP1 affect performance?
4) RAM usage on Vindictus.exe never exceeds 550M. Previously it would use upwards of 1Gig of RAM (for its graphics files or whatever?). This concerns me. Is it being limited somehow?

Any suggestions?

 

[Silmeria]

Seems to have been resolved by enabling a Swap file for the D:/ drive.
Game is installed on D:/.
Windows on C:/.
Does Windows not use C:/ swap space for D:/ programs?