Split second lockups

Hi, I have had this on and off for years, only on Nvidia rigs.
About once a minute I get a split second lock up, it’s usually when there’s a lot going on.
It’s been fine for a while, I had forgotten about it since the last update it’s really annoying!
About once a minute the whole game just freezes for about a second. Then carries on.
I have tried deleting and renaming the three files, ran the reset command. Repaired the game from the launcher. Nothing seems to work.
I7 4570k 16 gigs and a 6gig 1060.
Windows 10 pro 64 bit.