It's PIO (programmed input/output), not P10. Back when things were generally slow, and bus traces and transistors were at a real premium (OK, bus traces still are, but they're running at 1GHz+), it was a none-too-speedy way to transfer data to and from IDE drives, but is inferior to DMA (direct memory access), except as a compatibility hack. In PIO, the CPU does the bulk of the work in transferring data, and is limited in speed (the fastest PIO I think is about 16MB/s). With DMA, the CPU says, "move this here," and then moves on to other things while the transfer happens.
Right-click My Computer->properties->System->Device Manager
Under IDE ATA/ATAPI controllers, check both IDE channels' Advanced Properties. If any that are enabled are not set to, "DMA if available," and do not read "Ultra DMA Mode" or "Not Applicable" then there may be a problem. First, though, make sure they are set to DMA if available (if you have to change the setting, you'l need to reboot).
Still doing bad? I'd get the diagnostic tools for your drive (such as Seatools for a Seagate), and run a test or two (usually there's a short and a long). If that comes up clean, defrag. If it doesn't, stop the test (assuming it does not stop on an error), and back up your data immediately (back up first, worry about what to do after that later). Diags before defrag! If it's a hardware problem, you don't want to be stressing the drive as it quietly dies on you!