VERY slow file transfer from DVD to Desktop

I use DVD+RW to back up my data. When I actually needed to retrieve some of this data from discs, my DVD writers spin very slowly, make all sorts of noises and the file transfer speed from the disc to my Desktop is less than 100KB/sec. These are a mix of web pages, text files, .jpegs, .pdfs, etc. My chipset drivers are up to date, and DMA is enabled in Device Manager (IDE mode). AHCI mode...