I "fixed" my slow camera by going to settings then to mobile substrate add ons. Turn off camera related substrates As a test. I turned off snappy giggy and a few others then it locked up and rebooted. Now after reboot. Camera went from 10 seconds to 2-3 Seconds.
Started to think everything was slow but really only some apps.
I will test if It's just substrate access or the actual substrates I disabled.