Vsync explanation

Posting this to read later, because inevitably we all need a vsync refresh from time to time :)

https://hardforum.com/threads/how-vsync-works-and-why-people-loathe-it.928593/

This was linked from Mike Abrash's blog here: http://blogs.valvesoftware.com/abrash/raster-scan-displays-more-than-meets-the-eye/