Algodoo

You can prevent lag by designating the plane as a "killer". That way whenever items that fall to the ground (the plane) will immediately die, preventing a buildup of unneeded material. You do that by selecting "material" in the plane, then check the "killer" checkbox at the bottom. Then, of course you need to save the scene and upload it to Algobox.

Since you are new to Algodoo, it's perfectly Okay to ask technical questions in the comments section of a scene. You can do that in any of my own scenes or other users who have been here for a very long time (s_noonan is another good source of knowledge).

More: I forgot to mention that the killer plane must have the same collision layer enabled as the "junk" that you want to die when they hit the ground.

what plane...?

The plane located at the bottom section of the scene. It's invisible because you made it black like the rest of the scene, but if you click on it and use a lighter color, then it will show up. It's what the used up explosion pieces fall onto after the explosion. You can think of it as the ground.