It really depends on a huge number of variables. If you're playing in a massive server (like I usually do when I play) there are a lot more people to beat on but the average PL across the map usually stays around a million the entire time (as old people leave and new ones come in) which means you lose lots of PL whenever you die near a transformation. In smaller rooms things go more quickly as everybody has a bigger impact on the overall power levels in the room, and you'll transform pretty quickly even if you aren't doing a lot of damage. In melee only rooms PLs also grow much more slowly but you die less often, so it's a grab bag. In all cases, if you avoid death whenever possible and pick off the guys you know you can take out (No, I don't reccomend chasing one guy around the map for an hour) you'll gain enough to take control.