zlibnet

Compression test:

127 506 files (a svn wc) Original size: 3 443 130 254

zlibnet

compressed (default): 1,09 GB (1 178 180 638 bytes) time: 00:02:39.9731499

.NET 4.5 ZipArchive

compressed (optimal): 1,08 GB (1 168 228 598 bytes) time: 00:03:00.2553101

compressed (fastest): 1,18 GB (1 270 258 799 bytes) time: 00:02:00.8949148

ZipArchive performace is actually not that bad:-)