Ever since I installed the Creator’s Update, the performance for the GL Driver in windowed mode seems to have been cut in half (running at full screen with GL Driver still works properly)
Here are my specs: http://paste.debian.net/992049/
For the record, I tried with the latest trunk build to see if there was any fix to the problem…nope.
Yep, same here but it’s more like cut down by a factor of 10 - Windows shows RA using 100% of the GPU (a GTX1080) even without any content loaded.
But for me, it does that regardless of whether I run fullscreen or fullscreen windowed.
Sounds like you should raise this with Microsoft and/or Nvidia though, if they are pushing through updates that severely degrade OpenGL performance, that’s their fault.
Other than GZDoom - which runs fine, still - I have no other GL apps to test at the moment, so if this only affects RetroArch it means, as the months go by and more users are updated to the FCU, RA with the GL driver will become unusable for Windows users, which is pretty sad 
I wish anyone good luck who wants to try their hand at filing a bug report with Microsoft and having it not disappear into oblivion…
I got the Fall Creator’s Update a few days ago and am on the 387.92 Nvidia drivers. I don’t see a difference when running Kirby 64 on the old Glupen core with the GL driver in exclusive fullscreen or windowed. Either way it’s still full speed, no sound crackles. And if I unlock the framerate with spacebar it seems to fast forward the same speed (quite fast). I tested using today’s RA nightly. This is on an i5 2500k + 970 machine.
…I’m running a Radeon card…not an Nvidia card.