Ok, I did some more testing.
First, instead of creating the sprites every few seconds, I created 100 of them in a for loop in the On Start of layout event. It loaded them up fine and they started animating. After about 30 seconds, it crashed. So, creating them with a timer or all at once isn't a factor. But I thought it odd that it was able to create all of them and to run for 30 seconds before crashing. It 'feels' like a memory leak.
So, I wondered what the minimum was I could create and have it crash. While I haven't tested any lower than this, I changed the for loop to create just 5 of the Sprite3. Without applying any force, not moving the mouse, nothing... it took about 10 minutes but it crashed. So, a total of 6 sprites with the physics behavior enabled caused the JS to crash.
While, as I mentioned, this sounds like a bad memory leak, if this is a result of the memory limitation that Ashely increased, and if just 6 physics sprites reaches that limitation, then that's REALLY limiting what this game engine can do. And crashing is a really, really bad way of letting the developer know they've reached that limit.
I do hope this isn't working as intended. I have high hopes of purchasing this engine and putting it to good use.