DVD burner is super slow now?

Backing up my DVDs again since just about all my backups have denatured into unreadable. My burner, however, has become absurdly slow during the burning process. Encoding them onto the PC for backing up is the same and takes a reasonable amount of time. However, it took about 5 hours, last time, for it to burn 4gigs onto a DVD and the DVDs have popped out very hot. Now it DID work which was surprising cause I mean this DVD was hot. I think it's just overheating really quick and slowing itself down to keep from exploding but I have no idea why since I haven't changed anything on the computer that would cause it to do this. Any ideas on what might have happened or how to fix this?