Region Filter is a lightweight WoW addon for tagging the region and data centre location for groups in group finder. As an ex-OCE player, this was always frustrating because grouping with US servers meant 360ms or more.
If you are using the wonderful CurseBreaker please add this addon as a GitHub source and avoid giving CurseForge (soon/now Overwolf) the traffic.
You can do this by calling:
install gh:jamesb93/RegionFilter
Any bugs, please make a report here and if you have suggestions or PR's I'm happy to review them when I have the time.
The next major version will have a GUI for managing colours for each server region and datacentre group. I'll also try my best to make this work for EU, although I've heard that region-ing isn't as much as an issue on their client.