Clone Lag!

I'm working on a space exploration and base building game, and i need to reduce lag or the game is unplayable.
How do you make the game not lag when thousands of clones are being used? I don't want to make a 50x50 world due to lag!

LINK: StarmapOvis by new_account_pls_help | Snap! Build Your Own Blocks

Your link doesn't work - is it wrong or have you set your project to be shared?