Well, it's an empirical observation that Haskell programmers, however experienced they may be, are constantly surprised by the memory footprint of their programs — IIRC sometimes even the GHC's core developers get blindsided.
One of the ways to get lower latency is in fact to never deallocate and just ensure you won't run out of memory until the task is done.
I remember a story about a rocket which had a range limitation due to the amount if RAM onboard because it never freed any memory. When the engine of the rocket was upgraded, they simply doubled the RAM to let the firmware work for a longer time.