It's not that simple. A memory address is stored either locally or server side. You can mod local, you can't mod server-side.
Most mature game publishers would naturally put everything on the server-side for this exact reason. Independent self-publishing developers are often less funded and cannot afford larger more expensive servers capable of that amount of record-store and/or performance requirements.
Independents use a mixture of local and server, often putting anything competitive on the server---which I'm assuming are the speed modifiers you're asking about. I'm guessing the author already tried this and concluded they were stored server-side.