i need to compress som big file 600mb to 4.5Gb.
i need as god compression af possible but with fast decompression speed.
compression speed is ok to be slow.
comrpession requrimetns its ok to use up to 8gb of ram
Decomrpesseion memory req. must be below 2gb

so far i've used rep and CCM(x).
what id did was to use several trials wit different settings of ccm(x), and just keep the fast one without much increase in file size.
but even standard ccm has to slow decompression

what is the best way to to get god compression ratio with fast decompression?