Verdict: Irrelevant. Games like Street Fighter Alpha 3 or simple RPGs do not push the VU1 hard enough to matter. It won’t hurt to leave it on, but it won’t help either.

MTVU is a speed hack that offloads the VU1 (vector unit) emulation to a separate CPU core. Big performance boost on multi-core CPUs (3+ cores). Downside: Rarely causes sync issues in some games (e.g., Ratchet & Clank ).