LUCENE-1540 TrecContentSource moved from Java's GZipInputStream to common-compress 1.0.
This slowed down gzip decompression by a factor of 15.
Upgrading to 1.1 solves this problem.
I verified that the problem is only in GZIP, not in BZIP.
On the way, as 1.1 introduced constants for the compression methods, the code can be made a bit nicer.