This reminds me of a a hardware add-on for the IBM 360/370 computers in the 1970's.  IBM was beginning to incorporate paging and swapping into it's operating systems.  Hard drives at that time weren't very fast, but then, neither were the computers, so even though paging sped things up, it was still slow.  So this add-on was a lot of RAM, connected to a hard drive interface.  It looked like a hard drive from the OS side, but I/O performance was a lot closer to RAM than to a hard drive.  The price was also closer to the price of RAM, too.  This was back when a single RAM chip still had under 4K bits per chip (yeah, do the math on what 256 kilobytes would require). 

If the temporary file is small enough to fit into a virtual RAM drive, perhaps it would be just as smart to simply ask the developer to keep the information in memory, and not write it out until either the program ends, or the program knows persistent storage is required.

Finally, if temporary space is really required, why not put it on a fast thumb drive?  While not as fast as RAM, it's faster than a hard drive, and leaves more RAM available.