After a few tracks, my PC is starting to struggle a bit when overdubbing. Stangely, I can improve it by upping the project sampling speed but not sure why. Anyway, would combining the current tracks (once happy with them) into one track and then overdubbing, free up some processing power? I’m not sure how the tracks are processed when they are separate.
Using “Mix and Render” (Tracks menu) to mix down tracks into a single track, and thereby reducing the number of tracks may help a lot. Before you try that you may want to Export back-up copies of the individual tracks (Select the track so that it is highlighted, then use “File > Export Selection”).
The other possibility is that you may be running out of disk space, in which case the above will not help, so check that first.
It could be that the track sample rate and project sample rate don’t match, if so “Mix and Render” will fix that.
If you are on Windows Vista or 7, also see:
about matching sample rates in Windows and Audacity.
Thanks people. I shall mix and render and see what happens.