Tick mark in this box means that the game will download all patches/changes, instead of downloading them the first time you visit the affected sector(s).

I usually will do this, as I don't want to be heading off to some bygone sector then wait 10 minutes for it to load as it catches up on long-neglected patches. Yeah, I have to suffer longer on patch day(s) and immediately after a reinstall/new system, but to me it's worth it...