This is almost certainly not decompressor related, as the FreeDB archives come from a Unix FS. Have you read their FAQ? Here's the relevant section: http://www.freedb.org/en/faq.3.html#33 In any case, Kel's comment, as I understand it, refers to compressing the files. About 7-Zip, the only problem I'd expect might arise with sane archives (I'd expect anything to overflow if, say, dealing with millions of files) is insufficient memory: please note the memory requirements listed for compression and decompression as you select the compression options. Note that diminishing returns set in pretty quickly for most types of data, so it usually isn't economical to select the highest options anyway. Frankly, my concern regarding this potential issue exceeds saving a few mebibytes and transcends open- vs. closed-source feuds. At least from my PoV: I've been archiving a lot of data into multi-volume 7z archives with .PAR recovery data and I would like to know if some of that data is potentially lost.