The Hi compiler seemingly wasted memory. It used a stop and copy collector which just allocates a new to space by calling malloc and frees the from space afterwards. I did that on purpose such that even with multiple processes, you don't need double the size of memory.
I expected eager (FIFO) behavior from malloc, so I expected a malloc to just return the last slab of memory after a free. It didn't, it just would return a new memory segment. So seemingly, while the from space just is a few megabytes, it allocated new to spaces and would sit on the from spaces until the GC from malloc kicked it. So, it would take 500MB of memory, mostly unused and also freed, while running the compiler.
Fixed that behavior, don't think it matters much except for aesthetics, by implementing an intermediate pool.
Started a change to the runtime such that the FFI combinator memoizes the dl symbol and ffi CIF record.