Looks like the default allocator uses mmap(2) for every single allocation, which is horribly inefficient - you map a whole PAGE_SIZE worth of memory for every tiny string. Aside from just wasting memory this will make the TLB very unhappy.
It looks like sp_log's string formatting is entirely unbuffered which results in lots of tiny write syscalls.
It looks like sp_log's string formatting is entirely unbuffered which results in lots of tiny write syscalls.