I recently upgraded to 21.04 and after rebooting and installing upgrades, I've been finding one of my four cpu cores is generally at 100% constantly, with the whoopsie-upload-all command. It's been that way for about an hour so far.
I don't have a problem with uploading error and crash reports but the amount of CPU is now affecting my ability to work!
EDIT: The whoopsie process did finish, it just took longer than expected. Now I've got systemd-logind and systemd-journald taking up a bunch of CPU. I wonder if this is just part of the process after upgrading between Ubuntu versions?
I'm letting it run, but I've also tried the updated solution here:
systemd[1]: apport-autoreport.service: Failed with result 'start-limit-hit'
FURTHER UPDATE
the daemon-reload command didn't work, and journald continued to consistently chew up my CPU, so I eventually powered off the machine and rebooted.
There were a few error reports that came up after the reboot, and I sent them in, but no systemd or journald high-cpu usage anymore. I'm not sure if this was a loop or if the solution I tried above actually worked!