Well, the size limit of b.net is 3mb. Keep in mind that if your map is larger than 3mb you can't spread it throught battle.net . And in my opinion 2mb is the optimal size for a map. And keep in mind that big JASS systems (WEU's advanced triggers , Vexorian's caster system, just to name a few) take some space too. I think advanced triggers take more than 500kb. Heavy Lock and Vex's optimizer can clean the map from unnecesary things and make it run faster.