Slow write and read

A while back, my DVD+R drive started moving more slowly, and I really have no idea why. I have a NEC-1100a, I’m using Microsoft’s drivers, and the firmware is the rare 1.B0.
The drive supposedly writes at 4x, and it actually used to, but now I don’t think it’s even writing at 2.4x. Nero gives that time estimate when you burn a DVD, and it always undershoots by a lot. I wasn’t all too bothered by this because I didn’t burn a lot of DVD+Rs, but I think it’s reading them very slowly, too. I tried to copy a full disc of files to hard drive and Windows estimated over thirty minutes, which means it was probably going to take forty minutes, which is just about how long it takes to write a full DVD. Moreover, DVD video playback is pretty shaky, too. It’s quite touchy about my doing other things while I’m watching, and even if the video player is the only thing active, it hiccups every once in a while.
All this leads me to believe that the media is not the problem (been using Fujifilm and Ritek,) and I can’t seem to find a solution. Any ideas? Thanks in advance.