I haven't looked at the implementation, but this seems to imply it is very I/O intensive and already takes a very long time in RAM. Yet, nothing about the problem statement suggests it would be such a task --- it sounds like something that could be very straightforwardly done completely in memory.
It was only a couple minutes. That's a bit disappointing.
Oh man I gotta look into the composite glyphs. I don't know much about fonts in general. Thanks for this bit of information.
Maybe the programmer doesn't need to use this more than once?
If this program needed to operate from memory instead of a disk, why didn't the coder just... code it that way? Are they saying to use a RAM disk to ensure you don't encounter automatic paging out to disk by the OS?
It requires file paths, and it will be doing a large amount of reading. Easiest way of solving this is probably just to fake that your memory is a hard drive.