EB Configuration

[JaM]

Can somebody explain what "multirun" does in EB Configuration?

I have enabled something in preferences, and game now has some strange lag on campaign and during battles. Its definitly not my PC, as everything worked just fine before, thing is i dont remember what i changed exactly (but last time i remember i was checking that box in EB preferences...)

edit:
looks like i have figured out my lag issue - i have moved my RTW install to another drive, but that drive was not same as the original... i have a RAID main drive where I have all games installed and two other Data drives for data backups... and those are nowhere as fast...

anyway i'd still like to know what the multirun means..