If you are troubleshooting graphical bugs and need to make a GS dump to send to developers, MTVU can sometimes interfere with the accurate reproduction of the bug.
The setting is a speedhack in the PCSX2 emulator designed to improve performance by offloading Vector Unit 1 (VU1) processing to a separate CPU thread. mtvu pcsx2 upd
While compatible with over 99% of the library, MTVU can occasionally cause issues: If you are troubleshooting graphical bugs and need
major threading improvements + stability fixes. Re-enable MTVU for a free FPS boost in heavy PS2 games. mtvu pcsx2 upd