VSync causes significant performance loss

Validation

• I have checked the Issues page to see if my problem has already been reported
• [Irrelevant] I have confirmed that this bug does not occur in the original game running on original Xbox 360 hardware

Describe the Bug

In some areas, enabling VSync causes about a 25-30 FPS drop, testing with ShowFPS enabled.

Steps to Reproduce

Steps to reproduce the bug:

1. Enable VSync
2. All my frames gone ):

Expected Behavior

VSync shouldn't do that

Footage

VSync enabled:

VSync disabled:

Specifications

Fill out the following details:

• CPU: AMD Ryzen 7 3700X
• GPU: NVIDIA RTX 2070 Super
• GPU Driver: NVIDIA driver 565.77
• OS: NixOS 25.05 (Linux)
• Version: 1.0.0

If I were to guess I'd say this is NVIDIA and Linux exclusive, otherwise I would have expected someone else to open an issue by now.

Also, this is anecdotal, but the framerate seems to be even lower than what's reported with VSync on, which is why I think I managed to catch this.

Start by reproducing the issue on NixOS with the reported Ryzen 7 3700X, RTX 2070 Super, NVIDIA driver 565.77, and version 1.0.0, comparing ShowFPS results with VSync enabled and disabled in the affected areas. Trace the VSync and frame-pacing path used by the Linux build. Done means VSync no longer causes the reported 25–30 FPS loss or lower-than-reported frame rate in the affected scenario.