Blendmodes are handled by the 3d Hardware not software, disabling these could give an FPS boost on older 3D GFX hardware.
It will give a boost on newer cards, too. 3D effects come with a price and that price has always been and will always be performance :c/ BMax is currently using dated version of OpenGL and D3D and cannot even take "full" advantage of newer graphics cards. Granted in Eikon's case he is using a Radeon 7500 which came out back in 2001 and was a budget card. However, with the dated versions of OpenGL & D3D being used by BMax (which are equally as old, if not older than his video card), he should not be having any major performance hits.OGL under B+ still blows away BMax in performance.