Believe it or not, this is a common problem I experienced with all other screen capture applications, and the primary reason why I gave SC a try.
And like all other screen capture applications, SC did have the same issue for me, in the beginning, but at least mouser was willing to work to find a solution (which he did), and I no longer have the out of memory problem in SC. Can't say the same about the rest of the developers of those other apps.