[Fern]

I don't think it would make the server run slower since that's a feature that only operate on the client side.

It's not a background that would be need to be transfered throught the server.

In brief, it woudl source a file inside your computer, not a file inside the server, nor would it need to upload it on the server.

Yeah, exactly, the idea is that the background you choose is taken from a direct image link so there's no need for uploading (which, I don't know if that makes it not contribute to lag at all, but I imagine would be much better for the server overall.)