From your Safari menu bar click Safari > Preferences then select the Privacy tab.
Click: Remove All Website Data
Then delete the cache.
Open a Finder window. From the Finder menu bar click Go > Go to Folder
Type or copy paste the following
Click Go then move the Cache.db file to the Trash.
Quit and relaunch Safari to test.
If nothing above helped, troubleshoot Safari extensions.
From the Safari menu bar click Safari > Preferences then select the Extensions tab. Turn that OFF, quit and relaunch Safari to test.
If that helped, turn one extension on then quit and relaunch Safari to test until you find the incompatible extension then click uninstall.