I was doing ok with 8K maps but I changed the size to 41K and when I do a attrib map now the cores seem to lock up. I investigated the problem in the log and found that it would hang or get out of sync after about 5 minutes. I though maybe my processor was going bad but a hard test of the cores shows it to be fine.
It doesn't have any problems with the map in the released version but in this dev version it appears that the cores are not syncing correctly.
I set it to use 2 of the 4 cores and forced sync which appears to have fixed the problem but you may want to check it.
All is well with 2 cores