Plextor-712A DVD Burning Problem

Program: I use DVD Shrink and Nero (to burn)…
Media: Ridata 4x dvd+r
Computer: i have a pentium 2.4, 512 mb ram, and 200 gig hdd.

-----I used to be able to burn dvds at 8x (approx 8 or 9 minutes) and rip dvds really quickly. My computer would never lag and I could multitask while burning dvds. Recently my computer has been lagging (only when i burn) and burn time takes 20 mins or more (but dvd shrink states that it is burning at 8x)…
Has anyone here had this problem before and does anyone know how to fix this problem?
I HAVE NOT CHANGED any settings… this just happened recently
Please HELP!

make sure the drive is set to DMA instead of PIO mode. in plextools, under drive settings>advanced there’s a checkbox to enable DMA mode. also, read this entire thread: