You can make your communication more professional by spelling out initialisms the first time you use them and then following them with the initialism in brackets. Like this: garbage collector (GC). After that, you may use the initialism freely.
Sincerely, your bad initialism GC.
For the GC it sounds like they don’t have generations which means copying long-lived objects needlessly due to the generational hypothesis. Interesting idea with the mailbox allocator, but how do these two allocators interact? Is the heap non-regional, or are they allocating into separate regions?
But they only collect tiny actors spaces, no big consecutive heaps as usual. Anyway, you can always add a minor collection later, and benchmark it. She didn't write it, a friend did.