If you have a very old dual-core CPU, or if a specific game is crashing or showing extreme graphical errors, turn it off. Limitations and Potential Issues While MTVU is safe, it's not magic.
In the early days of PCSX2, the emulator processed these units largely in sequence on a single CPU thread. This was accurate, but slow. As games became more complex, the main CPU core became overwhelmed trying to calculate physics, geometry, and game logic simultaneously. mtvu pcsx2 upd
Typical reasons users seek "pcsx2 upd":