Archiving an workspace with lots of files (400k) leads to an 5 hours waiting time until the progress is finished when using Tar.gz method. Zip Method finishes in 2 minutes. Creating an tar.gz archive manually with gnu tar/gzip and default settings takes about 3-4 minutes.
Which compression level are you using? Consider lowering it or maybe even make it configurable. Are you using buffered streams?
Please fix this performance issue to make the method usable.