On Windows 7 x64 I'm seeing massive memory leaks. It's most apparent with map of Japan from http://uud.info, but it can be reproduced with latest City Navigator North America.
I have .gdb file with selected all 470 map segments (Japan 1:25000 Road Navigator), 40 waypoints, 9 routes and 2 tracks. I zoom in 4-5 times, zoom out, then select one route and select "Show Selected Route On Map" and MapSource takes 1.9GB of memory. After that map start to show all kind of artifacts since 2GB is address space limit for 32-bit applications.
It takes a bit more zooming in and out in 6-7 large North American cities but memory consumption also jumps north of 1GB very soon.
It did that with previous two versions. I tried MapSource v6.11.5 and memory usage never goes over 32MB. God, I forgot how fast that version is!