Why not simply ask the author to explain the reasoning behind the claims? Speed improvements could be relative to previous releases of that source, not necessarily relative to official source.

As I mentioned to you before, it is more efficient to eliminate the directory cache entirely than to continually dump and rebuild it, which may be all the speed improvement amounts to. File search speed within the emulation will certainly degrade sans cache, but how much it degrades depends on the performance of the host's storage system.

The author is clearly a programmer working under contract; his first name seems to be Olivier, but that's all I can be certain about, and the marketer seems to make marketing claims.

And of course you're right: I forgot that in my project, following your advice, I removed the directory cache entirely, instead of merely rebuilding it. My first message misstated your recommendation; apologies!

Those customers are also buying support for non-game dosbox system to run legacy dBase apps, something the dosbox team isn't interested in supporting.