This is something that has always made my noggin jogin
NA NW Community= Fastest
OC NW Community= Fastest
CN (Chinese (also Korean and Indonesian)) NW Community= Fastest
When there were Brazilian events = Fastest
NaS NA/CN = It was called God-Tier, but I think it was pretty close to fastest. Might be wrong...
Red and Blue EU/NA = Fastest
NA/CN/OC AZW = Fastest
Whigs And tories NA = (I Believe) Fastest
EU = medium