Try simplest of Mac troubleshooting steps.
- Launch Safari holding the shift key down and test.
2. Startup in Safe Mode: https://support.apple.com/en-us/HT201262
To exit Safe Mode, click in the menu bar and choose “Restart”.
3 Download EtreCheck, run it to see a system snapshot
https://etrecheck.com
Click “Free download” button,
Open Downloads folder, click on it to open, and then select ”Open”.
“Choose a problem” from the popup menu box, and then “Start EtreCheck” in the dialog.
Click “Share Report” button in the toolbar, select “Copy report” .
Paste the report when you reply.
Note: This is a diagnostic test.