GCs absolutely increase memory pressure overhead, or are so conservative that they practically lead to slow leaks. You have to keep that metadata of "what is and isn't a pointer" somewhere and that comes with a cost.
No it isn't. The GC has to touch that data, which means it's cache pressure, which means it's perf pressure.
> And, once again, GC is optional.
Sure, but it's an exclusive choice between memory safety and speed. Other languages let you have your cake and eat it too in that respect (Cyclone, Rust, etc.).