We're still experimenting over in this thread.

It seems the best thing to do to speed up heavy I/O, and avoid reboots during decompression, is to put your Debian image on a SD card. The next best thing is to put your swap on an SD card.

The simplest thing that seems to work for me is to make a little script, call it swaponoff or something, with two lines:

chmod +x swaponoff
sudo ./swaponoff
(then do the thing you were about to do)

I'll add this to the installer (just before the decompression) and upload it as a new version.