My game is lagging quite a bit so I was wonder which of these two methods would be the most effective, making a script that reduces lagging or reducing the number of parts by grouping them together. What do you guys think I should do?
There is no such thing as an anti-lag script. Or one that works, anyhow.
Reducing parts will help, if you have a ton of them right now.
The main thing you'll want to do is optimize your code.