Please enable guest logins and log in as Guest. Launch Safari and test. Same problem?
After testing, log out of the guest account and disable it if you wish.
From your Safari menu bar click Safari / Preferences then select the Security tab. Deselect: Enable plug ins Quit then relaunch Safari. If Safari speeds up loading pages, troubleshooting help here. Unsupported third-party add-ons may cause Safari to unexpectedly quit or have performance issues
Check Safari / Preferences - Extensions. If you have any installed, turn that off, quit, relaunch Safari.
Quit Safari. Open a Finder window select your Home folder in the Sidebar on the left. Then open the Library folder, then the Caches folder, then the com.apple.Safari folder. Move the cache.db file from the com.apple.Safari folder to the Trash. Relaunch Safari.
Check for Login Items: Open System Preferences/Accounts then select the Login Items tab. Delete any files or apps you have listed there. And go to /Library/Startup Items. Move any files in the Startup Items folder to the Trash.
Right or control click the MacintoshHD icon. Click Get Info. In the Get Info window you will see Capacity and Available. Make sure you always have a minimum of 15% free disk space.
From the Safari menu bar click Safari / Reset Safari. Select the top 7 buttons, click Reset.
Try Safari in another user account. Same problems there, then log back into your admin account, launch Disk Utility. /Applications/Utilities
Select MacintoshHD in the panel on the left then select the First Aid tab.
Click: Verify Disk (not Verify Disk Permissions). If the startup disk needs repairing, follow the instructions for Using Disk Utility to verify or repair disks
I've had the same problem for the past week and a half but I figured out. It wasn't Safari. It's your internet network. If you're on a wireless router, reset the router and create a new network. This solved the problem for me. I hope it help.