Is there a way to load assets to prevent lag?

There is a problem I get on my big games, random lag occurs! Now not just saying that, It might have to do with having too many items in ServerStorage or in Lighting. I'm wondering if items in these folders are valid, or rendered because they're definitely causing lots of lag in my games. To combat this lag, I try deleting all the stuff in these folders, but for in-game shops and things like that will need a place to copy items from. So is there a way I can load items from the roblox website to use during gameplay instead of having them sitting around in ServerStorage? I looked around roblox tutorials, and I want to know if this is the right code:

local Asset = 000000
game:GetService("InsertService"):LoadAsset(Asset).Parent = game.ServerStorage.Assets