Go step by step and test.
1. Click in the menu bar and choose “Force Quit”.
Select Safari and click “Force Quit at the bottom of the Force Quit window.
Hold the Shift key down and launch Safari.
2. Disable Extensions and test.
Safari > Preferences > Extensions
Uncheck boxes beside “Enable Extension” and test.
Enable Extensions one by one and test.
To uninstall any extension, select it and click the “Uninstall” button.
3. Delete Caches.
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”.
4. Delete Cookies.
Safari > Preferences > Privacy > Cookies and other website data:
Click the “Details” button.
Remove all cookies except ones from Apple, your internet service provider and banks.
5. Delete com.apple.Safari.plist file and test.
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. Relaunch Safari.
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”.
6. If this doesn’t help, please run EtreCheck and post the report here.
http://etresoft.com/etrecheck
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.