From Anselm D's comment in https://sourceforge.net/p/xowa/discussion/general/thread/72bb24b0/
Did you think about downloading, storing to a file (for later usage) and unpacking (with apache common) and "storing" to database in "one" step ("parallel")? This will reduce the time for installing, because the bottleneck should be the download.
This would allow a user to import a wiki faster while using no extra space.
Specifically, these are the scenarios
Scenario 1: Download, unzip, import:
Scenario 2: Download, import (directly from bz2 file):
Scenario 3: Import while downloading (proposed)