The newly released Booster v1.2.0 uses a new feature of Enonic XP 7.15 - Transient repositories.
They consume less disk space - if periodic Vacuuming is run.
NOTE: You need to stop booster app ,delete com.enonic.app.booster
repository and start booster app again in order for repository to become transient.
New version is on Enonic Market .