In case you haven't noticed, the only way to proper test a map is in fact putting into the rotation, otherwise gl getting 85+ players to help you test a map.
There are several variables that weight into the performance issue regarding this Game (read game, not mod), specially with such a "low/mediocre" net-coding from TW.
It's hard enough to the map maker to deal with such a limited editing system (for the love of god, it doesn't even have an "undo" feature ...) and limited amount of actually decent scene props to give us the best of both worlds.
As jacko said, I know of people with low machines, old stuff, dealing pretty well in maps like Swadian one, and if you enter edit mode you'll be in awe with the amount of details and props in usage there. A great job from mustikki indeed, one of my favorite.