I've noticed that burp-ui creates temporary files in /tmp during restore, once for restored files themselves and another time for .zip archive with them. This may create problems when it's running on a limited machine and restore size is large, especially since /tmp is RAM-based on many machines (fortunately it currenlty fails after 2GB).

Is it possible to switch to archiving on-the-fly instead? I don't know about zip (especially in pure Python), but certainly should be possible for tar.gz if you can afford to spawn extra processes.