I read about the load balance and how it should get better. For some reason, mine is getting worse. My laptop, which is the slowest of the machines seem to be getting all the work while my Xeon computer, the fastest, gets the smallest load. (As seen in the picture where the fastest machines after a couple of renders are down to a sliver)
Looking at that image and reading what James said, I think this must be an issue of the specific files being rendered. I'm not sure CrowdRender knows what pieces of your render are more complicated. this could maybe be done at some level with a fast low quality render and some data points beforehand?, but that's a pain.
I just rendered a test animation that doesn't have much of anything going on for like the first 50 frames in the left half. It's pretty much a solid colored plane. What happened over 8 computers rendering this was 5 would render really face, the other 3 take twice as long. Then the load balancer I believe would calculate and swap out the slow ones for the next frame, rinse repeat. Once the whole scene had as much going on everything balanced very nicely.