Summary

When V-sync is enabled, the frame rate is capped at double the screen rate. My screen refresh rate is at 144, so in game i have cap on 288 FPS ( should be 144 FPS)

Steps to reproduce

1. Set V-sync to ON, and render distance to relatively low values
2. Set max framerate to unlimited
3. Launch minecraft world and observe FPS on F3 debug screen

Observed results
Maximum FPS is ~288 FPS

Expected results

Maximum FPS should be ~144 FPS