Couple weeks ago had someone complain about system updates and other mildly IO heavy things making his system extremely slow and lock up for minutes at a time,

Couple weeks ago had someone complain about system updates and other mildly IO heavy things making his system extremely slow and lock up for minutes at a time, despite having an NVMe SSD. Rebalancing fixed it - which iirc I also had to do regularly about ten years ago when I had the exact same problems with btrfs.