Compression software with slow rates, and very high compression

Question

I have a lot of data that I don't have to 'get at right away', and I was wondering if there was any compression software I could use that could compress it down to a smaller size than I'm currently getting with 7zip. Compressing a gig of data takes ~10 minutes (optimizing for file size), and much less to decompress. Assuming I could spend hours on compression+extraction, would there be any way to get the compressed files even smaller?

So far, I've yet to see any GPU assisted compression programs, has anyone seen anything floating around?

Answer 1

http://en.wikipedia.org/wiki/Data_compression

This actually depends on what you are compressing, and if you need lossless compression or not.

Check out:

http://www.maximumcompression.com/index.html

It's a website with benchmarks for different data compression programs, testing them at various conditions and rating for various parameters (compress/decompress speed/ratio).

Answer 2

Jeff Atwood, our fearless leader, has a lot to say about file compression.

For what it's worth, 7-Zip's Ultra setting for 7z compression is probably the best you'll get when compressing several different file types.

Answer 3

One program that can sometimes improve compression ratio: cromfs

It creates compressed read-only filesystem that can have greater compression ratio than usual archive in some cases (although maximum number of blocks seems to be limited - compression is very memory-hungry).