When working on a laptop equipped with a FireWire audio device or DSP unit (such as TC Electronic Powercore FireWire), it may also be better to record audio to the internal drive rather than to an external FireWire device, as this places less demand on the FireWire bus bandwidth. You can always back up to the external FireWire device after recording. If in doubt, do a track count test with both the internal and external drives, and see which gives you the most tracks of recording or playback without glitching.
Another solution is to install a PCM-CIA-based (CardBus) FireWire card and running the recording drive off of that.