YES!
The game seems to work by using the special build from the vogons.zetafleet.com thread (cvsbuild65_pq.rar) and setting "core=prefetch" in the dosbox.conf file. Those Vogons are pretty smart, huh. Thanks for figuring it out!
So apparently the manual was wrong, it does seem like JetFighter used some special "prefetch queue" stuff, that was particular to the 80386 and earlier processors -- maybe they didn't know the real reason back then and customer service decided to blame those bad hard drive installs.
Incidentally, the thread mentions copy-protection, but I would think another aspect is that the game uses a lot of different executables to run; there are 13 executables, and as far as I can tell, only 3 other (necessary) files. So maybe they used those prefetch files to keep all the executables working together.
Okay, time to start playing through the game again...:thumbs: