I confirmed that is what the problem is: BUT, when one watches the memory monitor for a few seconds, it drops back down to 43 Megabytes!
This would indicate (to me at least) that garbage collection is taking place, but that the Snap! VM isn't triggering GC often enough to prevent a fast "loop" such as this from blowing the heap space.
Is there a means of calling a primitive to do GC once in a while as in every x items listed from a possibly consumed stream?
EDIT_ADD:
I do note that Snap!'s "Garbage Collection" may be nothing but to set references to JavaScript objects to nil's in order to let the JavaScript GC "do its thing" as required...