Since I got the new WordPress version my dashboard is slow

Since I got the new WordPress version my dashboard is slow, not just slow very slow. it was fine before the latest version can someone help?

I read a lot about it but all the threads were old so dont know if they apply on the new version of WordPress.

When i try to do two things at once like uploading images and add tags it gives me this error: Connection lost. Saving has been disabled until you’re reconnected. We’re backing up this post in your browser, just in case.

Please help