... or rather the lack of it. Getting this mega event very very early on a gigantic map totally ruins the fun of it. If a ship needs 50 turns to cross the galaxy, things get boring very early on.
There should be a solution to this mega event, e.g.
a) An extremely expensive tech (or a serious of expensive techs with small incremental effects) to negate this event over time
An option to disregard this event and eventually pay the price, like bermuda quadrants, traveling wormholes, ion storms, galaxy swallowing black holes and so on.