This might be to do with your Internet connection.
Also, your browser might be slow. To fix this, you should clean your history and/or sign out of your Opera account on the browser.
You can speed up the browser by uninstalling it and reinstalling. Simply find Opera, right click and select Uninstall. Confirm the uninstallation in the Control Panel. Then, install Opera using another browser, or by using the setup wizard if you still have it.
If you can't fix Opera, then you should use a different, modern web browser. I like Chrome, Firefox and the new Microsoft Edge.
Hope this helps!