Go step by step and test.
1. Delete Caches and test.
Close all windows and quit all applications.
Hold "option" key down and click "Go" menu in the Finder menu bar.
Select "Library" from the dropdown.
Library > Caches > com.apple.Safari
Right click the com.apple.Safari file and select "Move To Trash.
Close windows and relaunch Safari.
2. Delete com.apple.Safari.plist file and test.
Backup your Mac.
Empty the Trash.
Quit all applications.
Hold the option key down and click the "Go" menu in the Finder menu bar.
Select "Library" from the drop down.
Library > Preferences > com.apple.Safari.plist
Right click on it and select "Move it to Trash".
Restart and relaunch Safari. Click “Start using Safari” link at the bottom.
If this doesn’t help, “Put Back” the com.apple.Safari.plist
Right click on the Trash icon in the Dock and select “Open”.
Right click on the com.apple.Safari.plist and select “Put Back”.
3. Sometimes third party software can cause this kind of a problem.
Please run Etrecheck and post the report here.
Download it, open Downloads folder, click on it to open and select ”Open”.
Select a problem from the “Choose a problem” popup menu box, and then “Start EtreCheck” in the dialog.
Click “Share Report” button in the toolbar, select “Copy to Clipboard”, and then paste it when you reply.