[Dovecot] New mailbox format

[nodata]

> I've been doing some thinking on a new better mailbox format that'd be
> faster than mbox and maildir for most common uses. Comments welcome.
>
[snip]

Apologies for being rude, but I've not heard complaints about maildir
being slow. Is it? It would be nice to see benchmarks.

It seems like some kind of cache manager would solve the problem, if there
was one, but then some might say we'd be doing the job of the kernel.
Are there kernel parameters which can be tweaked to address the slowness?