http://bugs.winehq.org/show_bug.cgi?id=13122
--- Comment #24 from Stefan Dösinger stefandoesinger@gmx.at 2008-05-22 06:01:14 --- Commenting out GL_EXT_framebuffer_blit from the extension table in direct.c could show if it's a problem with fb_blit or not.
I guess the glCopyTexImage2D with offscreenrenderingmode != fbo causes the slow performance with multisampling.