You're wrong for like 6 different reasons.

If that were true you could have listed one the made sense in context. This person was saying that allocation was as fast as a incrementing a register while continually ignoring the fact that deallocation needs to happen along with any organization of allocated memory.

Then they were ignoring that large allocations have big speed benefits for a reason.

Conflating java moving a pointer, mapping memory into a process, sbrk, and arena allocation is going in circles, but the fundamentals that people need to fight the GC or work around it remains.

Allocations have a price and the first step to optimizing any program is avoiding that, but in GC languages you get pauses on top of your slow downs.