fidapple wrote:
It was the battery. One battery was faulty - trouble with waking up after sleep.
The second battery seemed fine but slowed down the computer. Somebody mentioned battery as potential reason. So replaced the battery again and everything is back to normal.
Glad you were able to figure it out.
FYI, the quality of third party Lithium Batteries is extremely poor even when purchased from respected vendors such as OWC and iFixIt (I would not purchase from anyone else because other vendors may vary stock based on price & not quality....one day you may get a "good" battery, the next you may get a bad one).
FYI, reinstalling macOS 10.15+ usually won't help because the macOS system files now reside on a read-only volume (from 11.x+ they reside on a signed & sealed volume as well). It is the user customizations (changing preferences and installation of third party apps) which tend to cause the problems. Erasing the system so any customizations are gone is what may help, but it is important not to restore them from a backup & to be very careful what third party software you install.....avoid the usual culprits known to cause problems......anti-virus apps, cleaning/optimizer apps, and third party security software....none of which are needed.
