Game is Experiencing Extreme Lag Everytime Players Join

Hello, I work for the group ‘Look_Lewis Projects’, and its game is currently experiencing massive lag every time players join the game. I am unsure of the issue and would like to receive help if that is ok.

Game:
https://www.roblox.com/games/5702705074/

DISCLAIMER:
I do not develop the game, and I am just serving as an unofficial representative to assist their game.

One, does your game have any free models? If that’s the case then ask the game developers to check the free models to see if there is any unnecessary stuff in the models/objects. Second, how many big this are their, it might be that it lags because the new player is loading everything and would start to break the server. And third, if multiple people joins, would the lag worsen?