A real-time Racket?

[Dimaugh Silvestris]

I was reading about Extempore, an enviroment for audio and video production in Scheme. Well, almost: it uses something similar to SuperCollider's client-server architechture, with a Scheme interpreter on the client side and a server in a typed Scheme with manual memory management, Xtlang. 
https://extemporelang.github.io/docs/reference/memory-management/

And I was thinking, well, we already have typed Racket, all we need now is a #lang where you can turn off the GC and have some way of doing manual memory management. Then maybe we can build applications where there is a lower level subprocess in realtime/racket and higher level process any of the GC #langs.
It just would be nice to be able to do such things without having to switch to C or some other low level language.

Probably I'm missing something that makes this harder than it sounds, though.