Chosen Solution
Hi, my Macbook Pro 2011 13” is extremely slow. Only if booted in safe mode its normal. System was installed completely new to High Sierra. Trying to reinstall the system: If i try internet recovery or boot from USB stick the grey progress bar gets stuck at the end and Macbook just shuts down. Tested with new hard drive, no difference. What else can I do? Safe mode seems to be ok… What could be the problem? :P
A bad battery may cause CPU throttling and if diagnostic warns the battery is bad, I wouldn’t be surprised that’s what the slowing down comes from. Try disconnecting battery from the logic board and see if that fixes the issue.
This is obviously a software issue. Let’s see what is running in the background after you boot. Do a “Force Quit” by hitting the Command, Option and Escape button at the same time. This will bring up a list possible items that you need to get out of there. To stop these on start up, go Under to Apple tp: System Preferences > Users & Groups > Log in items Now get rid of those items you don’t want. BTW I always change out the hard drive/IR cable on this model to the 2012 cable and usually then add an SSD and up it to 8 GB of RAM.
I have a similar problem. Only that when I plug in my MacBook and it works on power adapter and not on battery, it works very fine. But once I disconnect it, it works really slowly. If I boot into safe mode, it works fine too. Maybe you should try using your MacBook while plugged in to see?
