Significant PC lag while restic is running

This is a strange one, because I can’t see why it would be happening. I have some restic backups run every hour (one at a time, in sequence) and I’m getting noticeable lag in Windows 10 while it’s running. My cursor and sometimes keyboard input even lag. But most usage is low (I already set GOMAXPROCS=1 to try to combat this): maybe 30% total CPU with 6% from restic, 55% memory usage but only 300MB from restic, windows saying about 15% disk usage which is around 50MB/s from restic and should be almost all on my non-system drive, and about half my network at 200Mbps.

I’m not sure anyone will have an answer for me but I figured I might as well try, because it doesn’t make much sense to me. Even with massive resource usage I don’t usually see my cursor movement lagging (it’s wireless but I just replaced the battery and it has its own 2.4GHz dongle).

Edit: seems to be related to a VM running at the same time which has access to the same HDD. Not sure why it would slow down Windows so much though.

What sort of disk do you have? SSD or old spinning type?

SSD for system, HDDs for storage (all fairly good quality). I added files to storage so that’s mostly what restic was working on.

It’s probably your PC isn’t able to handle all the working on the storage then, causing lots of interrupts etc.

As a way of testing, what if you run a stress-ng test against your storage disk - do you see the same sort of issues?

So I was running a VM at the same time which I didn’t think was the issue because I closed the VM and it continued being laggy for minutes afterwards, but I just let it run with the VM shut down and it didn’t seem to lag much other than a second or two near the end which I probably wouldn’t notice if I wasn’t looking for it. The VM also has access to some folders on the HDD so it looks like that was probably the issue? I’ll have to watch it again when it has more data to upload. Still not sure why the non-OS HDD or potentially the high network usage would cause such a slowdown in the Windows UI but that seems like it’s probably the cause at least. Thanks for the responses though!