Lots of Minecraft boxes causing lag?

I have had a relatively large warehouse since the warehouse was built. I'm sure that it is because of the boxes, because I removed them with Worldedit as a test, after which they were suddenly gone. As soon as the boxes were back, the laggs were back. Now I don't know if you can fix it somehow.

How am I supposed to know?

Something is heavily computer dependent.

You can save something by assigning more ram to Minecraft, but that's only half the battle. You can also make sure that things go better in the game. Turn down the render distance, etc. And if you want to store more anyway, then maybe install Mod AE 2.