Spawn a bot. Color it black. Set it's scale to be really flat horizontally. Done.
Wouldn't that take up like a bajillion times more resources tho, especially if someone built a stadium with a few hundred seats that need to be filled?
I had 128 bots in a vicinity of eachother whilst walking around pseudo-randomly. I didn't experience any lag and nor did other players.
I think it'll be ok.
That's also because Port has a supercomputer.
It would be way less efficient than planting a few hundred bricks