6 physics objects destroying performance in platformer?

So working on a game just sorta playing around and I have a very strange issue, maybe it's known, but it seems very limiting, unless I'm doing something wrong.

I have some stacked boxes that I want my hero to slash and destroy with his sword, it plays fine for the most part, but the longer I let the level sit, it slows down to a crawl and the frame rate just dies. I finally figured out it is the 6 boxes with physics and Solid enabled on them, they are stacked 3 high.

Does 6 boxes with physic really slow down this engine that much? It's to the point that if it sits for more then 5 minutes or so it crashes my browser.

I feel like I'm doing something wrong or not thinking about some aspect of this, I know I've built games with more then 6 physics items.

Playing around further the slow down is the same with only 4 boxes that are not stacked.

Slow down happens after about 4 minutes. There are only 6 total objects in the layout, my character, the floor and the 4 boxes.

So messing around with it more, it seems like it was my event sheet that was spawning a particle system to make the box explode, I'll go over how I set it up, but not sure why that would slow things down that significantly.

Particles may have a significant impact on performance, and if you are constantly creating new particle objects, no wonder they are slowing your game down.