UPDATE:

After almost two hours of fiddling (essentially an exercise in doing the same things over and over hoping for different results) the game suddenly started behaving correctly. I was able to play both old files and new games without the movement issue. It's like it .. fixed itself? Not quite sure what happened there. I'm just happy that the darn thing is back to working like it's supposed to. Should anyone have insight into what might have caused the game to misbehave though, I'd certainly be interested in hearing it.

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ORIGINAL MESSAGE:

I've seen a lot of issues with this for people on controllers but no one talking about keyboard problems. I simply can't find a solution. I played the Witcher last year (pre DLC) before my computer crashed. I had no problems at the time and everything worked properly. Now repaired, my computer is now the exact same machine - just with a few repairs. I recently found my old saves and started a new game so I could re-orient myself with controls.

Geralt is INCREDIBLY unresponsive.
- He doesn't stop walking for a good 5-10 seconds after I stop pressing W.
- He usually refuses to turn with I tell him to OR or he'll turn at first but then get stuck in that direction and just start walking in circles/on the diagonal.
- When he's not refusing to turn properly, he turns but only super, super fast - and generally a good second or two after I gave him the command to do so.

Trouble shooting I've done:
- Switched to a wired keyboard. Both the wired and wireless keyboards had the exact same problem.
- Game is up to date with most recent patches
- Tested both wireless and wired mouse. Same as above.
- Update drivers for all mice and keyboards. Problems persisted.
- Changed location, as in painstakingly leaving the tower and entering the wall running tutorial (just in case). Problems persisted.
- DRASTICALLY lowered visual setting in case there was some kind of visuals induced lag. Problems persisted.

Other factors to consider:
- Mouse cursor speed is perfect when not trying to move. Cut scenes and standing still movement are spot on.
- Windows 10 in general has been updated. Problems persist.
- Game has been verified/repaired in GOG Galaxy (just in case). Problems persist.
- Tried running Witcher 3 independently of GOG Galaxy, but it insisted upon opening Galaxy and wouldn't let me do so.
- I have the game + expansions installed individually- not GotY version.

When I looked online for solutions people with this problem seemed to fix it by replacing their controller, updating drivers, or using a wired controller. None of these thing either help or are relevant.

Does anyone have any advice?

Computer "crashed". Computer repaired. Computer behaving differently. Sounds like a shoddy repair to me.

The computer runs fine otherwise, and has done so for the past 8 months. Witcher 3 is the only thing that has given me problems. I'd have certainly bothered mentioning otherwise if that weren't the case.

You would also note that I've noticed other people online had the same issue.

the lagging glitch was caused by the last galaxy update and has affected many players. i've tried a few things too and still have the problem, so sadly i can't really play rght now.

You use Galaxy?...because I disabled the overlay and cloud, and play ok...

Sorry to hear that others are having this problem! Mine ultimately fixed itself somehow after I set all the visuals to low, and then increased them one by one - reentering the game between each setting. If people are pinpointing the galaxy update as the problem's origin, then maybe the update is conflicting with one of the higher visual settings?

Hopefully mine is not just a temporary reprieve. If it keeps behaving, and if I can figure out what I did to make it work again, I'll let y'all know.

@pigulici: Thanks, that did it. Works now.

@pigulici Thank you, it works for me, too.