Wow to respond to all of these:
If explosions are slow then disable anisotropic filtering (set it to zero) either in the launcher or STAN_OGL.cfg. This is a drain at high resolutions (and somewhat pointless on explosions but atm I don't know what texture I'm loading so can't enable/disable on a case by case basis).
The dll... is not really a wrapper, origin did did us a big favour, put the hardware dependent implementations in dlls, the game is very clever, it automatically detects matching dlls. For more information see 3D Game Engine Programming, interestingly, not only is it the only other place I've seen this done but the author mentions that he first used the engine to create a Wing Commander style title. Its a safe bet that he was inspired by Prophecy.
If the menus are slow then disable scaling in STAN_OGL.cfg. This is an expensive operation, it pushes one of my cores to about 60%, so older machines should not use this. If it is slow in game however that is a different issue, bitmaps are scaled differently when the belief is that we're in game.