CPU is at 100 until I open task manager

Ever since I uninstalled BitDefender my computer has been acting weird. The biggest issue is even with absolutely nothing open, when I open task manager my cpu usage is at 100 then it drops down to normal levels, around 10-20%. If I close task manager and instantly open it back up, it’s back at 100%. How can I fix this?

It also takes me about 5 mins of sitting at the login screen after I type my password to actually get into my computer which started happening the exact same time as the cpu problem.