> garbage collection is just unacceptable: it introduces jitter
No it doesn't, not if you do it right. Incremental garbage collectors have been around for years, and measurements have generally shown that performance doesn't suffer significantly as long as enough memory is available, even with conservative garbage collectors like Boehm GC. Otoh, what people continuously push to the back of their mind is that calling free(3) isn't free. It does take time to free a big data structure.