GBDE performance on ZIP disks

Hi,

is there a way to speed up writing to a gbde encrypted ZIP disk?
Copying 37 MB of data to an encrypted disk (in a SCSI drive) that has
been initialized with "newfs -O 2 -U /dev/da1a.bde" takes ~180 seconds,
which is ~200KB/s. Copying the same amount of data to the disk without
using gbde takes ~50 seconds, which is ~740KB/s.

I guess this problem is similar to the one you have when using msdosfs
on a SCSI ZIP drive, which is also very slow.

Using a different sector size than the default 512, which is also the
sector size of the media, doesn't seem to be possible and always results
in a "gbde: write sector 0: Operation not permitted". Playing around
with newfs's options didn't help so far, either.

Stefan