Emulating PS2 from a disc

I've figured out a good combination of drivers and settings to emulate PS2 reasonably (compared to other things out there) smoothly...The only problem I'm having is that my computer can't upload data fast enough off the hard drive...is there any emulator that allows you to run a PS2 game from the disc so i can possibly get it to upload data from my hard drive and my disc drive? getting an external hard drive should work but I don't want to spend $100 just for an emulator to work (and theres still a chance it may not)