This still doesn't make sense. It doesn't take a full year to do optimizations like this. Maybe a month at most if you include the investigation time. And the memory usage is $150 times the number of users which is in the thousands at least.
Tragedy of folks forgetting how to program.
This mmap() "trick" isn't a trick, its a standard practice for anyone who has cut their teeth on POSIX or embedded. See also mlock()/munlock() ..