[3.x] Disable V-Sync and use optimized FPS limit

[Calinou]

This has some benefits over V-Sync:

• TPS demo is prone to stuttering and unstable frametimes. Disabling V-Sync helps make those issues less noticeable.
• Reduced input latency is useful for games with mouse aiming.

This comes at the cost of tearing, but it's usually not too noticeable in the TPS demo. Eventually, an option to re-enable V-Sync could be added to the options menu.

I recommend testing this PR on your own machine and see how it behaves in practice. Even on high-end GPUs, it often makes the demo feel smoother as you walk around the scene.