- To delete your history and cookies, go to Settings->Safari and select Clear History and Website Data from the drop-down menu. This will erase your Safari app's browsing history, cookies, and browsing data without affecting your autofill information.
- Go to Settings->Safari->Advanced-> Website Data, then pick the option to Remove All Website Data to delete cookies while keeping your history.
To finish the procedure, follow the onscreen instructions and then close the Safari program. Try launching the Safari app and browsing the Internet after a few seconds to check whether your browsing performance has improved.
If it continues to be very slow, then you may need to resort to a system reset to clear and refresh the network functions of your iPhone.
