As an alternative to Gzip, BZIP2, LZMA, and LZO, the Linux kernel can now be compressed using LZ4. The upstream LZ4 implementation has compression and decompression speeds easily beating LZO, Snappy, zlib, and other compression alternatives.
The LZ4 results for a Linux kernel image is that on an ARMv7 1.5GHz board the LZ4 compression speeds can top out at 45.6MB/s compared to 25.2MB/s and for a completely different ARM board the gains are similar of 86.7 MB/s versus 34.1/52.2 MB/s with LZO. This Linux kernel work was done by LG Electronics.
Right now though it appears the LZ4 Linux kernel support is for ARM hardware only though support could be added to other architectures. The LZ4 Linux 3.11 commits can be found through CGit.