Update 27-10-2018: The performance penalty WAS manifesting itself in all games after all, but was not always very obvious. It almost looked like my GPU shader units got cut in half. In the end, I tried doing a clean install of 1803 and... the problem PERSISTED. Thus, it couldn't have been related to 1809, but must've been a hardware bug, no? - YES! I removed my graphics card, cleaned the PCIe fingers on it with WD-40, as well as the slot on my motherboard... and voila! No more problems. So the GPU probably didn't get all the PCIe lanes because of a faulty contact and probably got choked by being degraded to a 1x or 2x PCIe interface. Weird as f. Update: After a lot more hours of research and testing, I've conclusively isolated the problem to IDtech6 games (so, Doom 2016 and Wolfenstein 2). Absolutely all other games run just fine after I've disabled spectre and meltdown protection via inSpectre. Also, it's not Vulkan per se, as vkQuake runs as usual, between 480 and 500 fps. Any thoughts? Original post: Hello! I turn to you good and smart people, for guidance, for I'm a fellow gamer in need... Ever since my system auto-updated to this Win10 October update, my games have been experiencing severe fps dips, far worse than I ever had on my system. I've observed such behaviour in Overwatch, SOTTR and CS:GO. But the worst offender, by far, is Doom (2016) - when all in-game statistics are showing, the GPU graph periodically shows a 3-5 second red lagspike that tanks fps to the high 20s (before the win update, fps never dipped below 80). These don't seem to be caused by anything on screen in particular - like particle effects or many monsters / geometry - they're random. The numerical ms display for CPU also periodically shows random very long red number stings instead of the XX.XX ms value. Never seen that. Resource monitor, windows task manager and MSI afterburner all show the GPU being pegged to 100% (tested it with vsync off) and the CPU being utilised pretty much like normal while playing DOOM (40-70% for my CPU). The framerate dips are real though - it's not only the numbers showing, you can really feel your mouse lag pretty hard - just like when playing at below 30 fps! My hardware: Asrock P67 Pro, non-oc 2500k, 8 GB 1333 DDR3, MSI GTX970, Samusng 830 SATA SSD, Sound BlasterX AE-5. What I tried: - cleaning dust out of my case, removing the GPU, cleaning dust and such... - tweaking and tuning windows - disabling unneeded functionality, including group policy-ing win defender, disabling telemetry via OOSU10 and such - uninstalling all metro apps, including the store - installing the latest intel chipset drivers (actually noticeably improved my network performance!) - uninstalling my video drivers via DDU in safe mode, clean installing v416.16 - doing the same for 416.34 - trying out pretty much every nvidia control panel setting. - enabling and disabling "game mode" in windows settings - in DOOM, switching to OpenGL (even worse performance) The very dubious part of the whole story is that at one point (3 days ago), without me having any apparent influence on it, the problem was suddenly gone... and then, today, windows auto-installed the patch tuesday cummulative update for 1809... and the problems returned. I am quite baffled by this phenomena. Never seen anything like it. And... to make it even more troubling - windows itself and pretty much everything except games works even better / snappier than before! /facepalm Does anyone have an inking about what the hell is going on? Any constructive thoughts would be greatly appreciated.