We (actually Marko) did a small comparison of xz and gzip compression algorithms that might come handy also to others. Here are the results on 2GB sample nginx log file: Compressed size: xz: 301MB (15% of original size) gzip: 454MB (22%)
Compression time: xz: 1242 seconds gzip: 261 seconds
Decompression time: xz: 40 seconds gzip: 36 seconds
Another difference between xz and gzip is that xz consumes several times more memory than gzip, which might become a constraint in some situations.