You're welcome. I'm sorry, but I don't understand why it would be lagging you out unless you have just a huge number of my chests. It only runs the script on those chests.
As for making the chests bigger on the inside, in the settings, you can set the size to either 48 or 96. I didn't want to make it any bigger than that so as to not break the game. If you want to make it bigger, in the settings.lua file for the mod, change the line
allowed_values = {48, 96},
to
allowed_values = {48, 96, 144},
and so on, just make sure all the options are multiples of 48.