Same here ever since patch last week game runs fine at 144hrz and then every 3 mins or so game freeze/shutter fps drops and hrz’s go to 20-30; then back to 144hrz and g-sync is fine for 3 whole mins.
Before i get a mod msg; updated nvidia/network and bios (was a pain but done) And no ryzer synapse software and windows 10 was recently updated automatically. So its either windows 10 update or blizzard update when all the issues started last week. Also happens in HOTS too.