Speedup factor for special cases of a number of sub-grids spread uniformly in the coarse mesh as a function of the number of processors. The special case here is that no re-refinement is done, and hence this represents an ideal problem for distributing AMR. In red are the results for 8 grids (2 per side), in green are the results for 64 grids, and blue shows results for 125 grids (5 per side). The purple shows the ideal case. Performance saturates roughly when the number of processors reaches the half the number of grids.