Ran out of memory

I have had several cases where Mindmanager has given me "Ran out of memory!" popups. It seems to be related to either of two very large maps. For the map that is causing it now I closed all other maps and checked the memory consumption in Task Manager; when I first looked (a few minutes after I saw the message) it said 32 MB, but as I watched it continued to climb to 48 MB and is now 64 MB (memory leak?).

So wondering if there is a limit on the size of maps, or if this is a bug that Mindmanager wants to fix.