Since my co-workers and I moved to DX9 we've noticed an intermittent stutter in our engine that appears to get worse the more geometry is on screen. The stutter isn't just visual, however, but also affects audio and other subsystems, including systems that are running in independent threads like MS text-to-speech. We've seen this stutter occur on all versions of DX9(a and b, retail and debug), on GeForce 3 and 4, on Radeon 9700 and 9800. On the audio side, we've heard the issue on Sound Blaster Live and Turtle Beach Santa Cruz cards and under DirectSound and Windows Multimedia. Has anyone else seen anything like this? Any ideas or suggestions?