I just finished backing up ~100GB to an external hard drive, during which my computer was very unresponsive even though my CPU and memory usage were very low and my operating system is installed on a separate SSD (not the one I'm copying from).
When the backup had finished I "safely removed" the external SSD, then waited for the popup to tell me I could unplug it before finally unplugging the hard drive.
Then I noticed my computer was still very unresponsive so I rebooted it and everything was back to normal, until I tried watching a YouTube video in full screen. I'm only seeing a few frames per second and system monitor shows 1 CPU core at 100% while the video is playing. It's not just YouTube either, every site is slow and unresponsive.
I should maybe also mention that before backing up to an external hard drive I had first tried to copy my files to an internal hard drive instead, but I was getting a lot of I/O errors and after a bit of fiddling trying to see if the drive was dead I ended up removing it from my system because it wasn't getting recognized at all anymore. While messing with the broken hard drive Firefox was still working fine as far as I remember.
Only Firefox is slow, other programs, even other web browsers or web based apps seem to be running fine. I did get a few dropped frames while testing full screen video in chrome but the video still looked smooth and I don't usually use chrome so I'm sure if that's normal.
I have tried:
- reinstalling Firefox
- using a new blank profile
- messing with Firefox performance settings
- updating graphics drivers
- rebooting my computer multiple times throughout each of these changes
- OS: Ubuntu 18.04.5 LTS x86_64
- Kernel: 4.15.0-128-generic
- CPU: Intel i7-8700k (12) @ 4.700GHz
- GPU: Nvidia GeForce GTX 1080
- Memory: 4x 8GiB @ 3200MHz
Any help is much appreciated.
EDIT: It's not just Firefox!
After some more testing it seems my GPU usage also hits 100% when doing anything in Firefox. Steam, however, is also very slow and hits 100% on my GPU when interacting with the program in any way.
Minecraft runs fine though, at a steady 130fps and 35% GPU usage.
gfx.webrender.enabled Firefox runs fine again, but that's not a fix, it's a workaround. Firefox used to run fine with webrender disabled and steam still doesn't run very well unless I disable hardware acceleration, but that doesn't make any sense. What's going on here?
EDIT 3: Firefox with webrender disabled and steam with hardware acceleration enabled are very smooth on the same computer running Windows 10 instead of Ubuntu.