DelphiX -IS- outdated. If you want high resolutions, lots of pixels and blinding graphics, dump it. You are WAY better of using a 3D engine (which uses DX3D/OpenGL, I don't care) which can use hardware acceleration. DelphiX hardly uses any hardware, so using a screensize of approx 2.5 times your old resolution, also slows your program down 2.5 times.

Oh, and what is VSync set to? For best speed you'd like it to be Off (DXDraw.Options I think it is?)...