Yeah, the Intel GMA does well in some aspects of the DirectX/OpenGL acceleration, and falls flat on its face in others. I have a 12 year old laptop that has a 32MB Radeon 7500 chip which runs circles around the GMA965 in most games, including Eschalon and some Quake/Quake 2 ports with fancy shader functions.
It's like taking a V8 powered car and giving it a straw for an exhaust pipe.
I do feel that Eschalon *could* be faster, but it's also being held back by the programming language. Sometimes the shorter learning curve comes at a cost, and obviously it's not going to be worth it for BW to learn a completely new programming language at this point just to save a few FPS. Perhaps for the next series, the new style combined with lessons from Eschalon will allow him to craft a game engine that will run like butter on everyone's computer!