Signal backups and lockups

I had my Signal app set to keep up to 500 messages of history. It seems to hit a point, maybe around a few hundred messages, where it totally pegs the CPU on my device, and makes the whole device unusable. Then it is time to reduce the back log. This can be done after taking backup, if message history is important.

In the settings, enable the backup. Let it finish. Then enable USB Debugging, plug the device in, and fetch the backup file with adb: adb -d pull /sdcard/Signal/Backups/signal-2020-08-20-01-24-38.backup. Then backups can be disabled again to save disk space on the device. Then to delete old history, set the message count to something lower, like 100 messages, and trigger the cleanup. After that finishes (it can take a while), set the message history back up to something like 500.