Well, there are a few ways to go about this:

1) Use FFSv2 instead of FFSv1 (add the -O2 to newfs).
2) Use LFS instead of FFS; this is the fastest, and LFS _CAN_ be
stable enough for production use if one is cognizant of the risks,
etc.
3) Use a larger filesystem block and frag size. Unless you have lots
of small files, you can easily bump it up to 32k bsize/4k fsize
without incident and get a slight performance increase and decreased
fsck time.

Many users combine (1) and (3), though (2) is the best solution
assuming you do not have to use ffs.
However, you specified ffs, so ... ;)

Good luck,

--Blair

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