Using a simple script:

#!/bin/sh

input="$1"
base=`echo $1 | sed 's/.jar$//'`
output="$base.pack.gz"

echo -n "Compressing $input ..."
pack200 -q "$output" "$input"
if [ $? -eq 0 ]; then
rm -f "$input"
echo " success"
else
rm -f "$output"
echo " failed"
fi

and running

user@work : ~/distribution-karaf-0.5.0-SNAPSHOT/system$ time find . -name *.jar | sort -u | xargs -n 1 ~/p.sh
real 9m49.336s
user 30m25.764s
sys 1m41.299s

results in ~50% size savings in the resulting distrution. It is non-functional because feature:install fails to install, but that is something that could be fixed by an appropriate plugin into karaf.

Investigate how this could be integrated into our simultaneous release distribution.