My bro has FX 8350 and 2 Radeon 280x, everything was working fine for 15-20 hours now all of a sudden it stutters and every 10 seconds the frames drop below 15, from 60. Is this normal? It came randomly out of no where, now it wont go away. It plays at 60, then it drops to around 10, 15 for few seconds and then back up, rinse and repeat. It's chaos. NO warning and no reason.

Try this. Quote from - A compendium of tweaks and fixes for the PC version

0e. Deleting your "user.settings" and "user.settings.bak" files after a new patch

To avoid any possible performance deterioration as a result of patching the game to a newer version after applying the .ini tweaks below, it is best to navigate to your ".../Documents/The Witcher 3" folder and delete the "user.settings" and "user.settings.bak" files, then start up the game as normal, reset your settings to what they were before and only after that reapply all of the .ini tweaks that you had before!

8. Fix stuttering caused by too frequent garbage collection

The game uses a garbage collection algorithm to clear up assets that are no longer required as you play the game, but its low default upper memory limit can cause stuttering in crowded places, most notably Novigrad. To force garbage collection to trigger less frequently and thus reduce/eliminate its associated stuttering, navigate to "...\The Witcher 3 Wild Hunt\bin\config\base" and open "gc.ini" with a text editor (e.g. Notepad), then find and tweak the following variable:

ObjectMemoryTrigger=512

HEY GUYS, I solved this problem with a ridiculous thing.... JUST UN-CHECK THE "GAME OVERLAY" IN THE GoG's Witcher 3 Settings I tried many tips in the web, reinstall im my 2 HDs... and nothing, i just do that and really solve my problem!!!

I might be wrong, but this tip could be deprecated, since there no longer is a "ObjectMemoryTrigger=<Value>" variable. Similar tweaks are possible, but I think this one does not work any longer.

Wow this old as crap post got revived, but I started having this issue a few days ago.

I could normally run W3 on a combo of high-ultra settings no problem. Past week started getting really bad frame rate issues to where I had to play on Medium to run it smoothly.

I tried the fix where you delete the .bak files and that appears to have worked. Im running most things on Ultra now and dont have any issues.

Didn't even notice how old this thread was, when I posted my response :D

Thanks, this worked. I know this is an old thread but I'm just gonna leave these keywords here in case anyone else googles this. AMD card witcher 3 stutter lag fps drop fix