We are currently using RTpatch software to build the binary difference between a update release (5.0uX) and it's baseline release (5.0). By default, RTPatch will use it's software to compress the binary diff, and then our installer will use lzx compression to compress further. However, there is no reason to have 2 separate compressors.
By using the NOCOMPRESS rtpatch flag, we can turn the rtpatch compression off, and only use our lzx compression. This will reduce the download of all JRE full installs as well as updates by 264KB. Also, because there is only 1 uncompression, it will make our installers somewhat faster (I haven't done any benchmarks on this yet).
The saving should be relatively bigger for the JDK installer also.