It's an issue that gets no attention. Arguably it has improved since the last update. Before that crashes were every 10 minutes if, as suggested, you were doing a lot of merging. A crash just means the program stops running and closes with no notice. A restart shows nothing seems to have gone wrong.
I'd say the minimum recommended by Ancestry is wrong. The 1 GB they recommend has to be shared by all the other operating systems and other programs running.
Everyone acknowledges that even with several GB of RAM the program can crash. It uses ridiculous amounts of RAM. Why? Nothing else I've ever run uses anywhere near that amount. Can anyone give me an example of a common program that does?