Jumpy Accuracy: Is it normal?

[FullMetaru]

As stated on the thread title, is it normal for USB devices (guitars and drums) to have jumpy accuracy? I've been playing for a bit on my PS3 drumset, and somehow I would steadily go at around -20 to 20 ms accuracy, then all of a sudden it would jump to -71 or 40 ms. I've also had this problem on my gamepad when I play other games. Sometimes the devices have lag spikes, so to speak, where there's a delay or dropped input.

Asus P5N-E SLI on nVIDIA 650i SLI
Intel Core2Quad Q6600
A-Data 2GB DDR2-800 RAM
nVIDIA GeForce 9500GT
4+1 USB devices plugged in (the +1 is the drumset or guitar)

[twuk]

I'm almost positive that it has to do with the PS3 usb devices. I bought a PS3 Les Paul specifically for FOF last year and I noticed the ridiculous lag spikes that you're about too so I just traded it in and got myself an explorer. Don't know too much about the drums though.

[FullMetaru]

Well the problem is, it's also happening with my XFX Gamepad, not just my drumset. Sometimes it doesn't register a button press fast enough or it doesn't register at all. At least with my drums I don't have dropped notes (none that I can see).