The Ubuntu Kernel Team benchmarked six compression methods for the initramfs, including BZIP2, GZIP, LZ4, LZMA, LZMO and XZ, to measure the loading time of the Linux kernel, as well as the decompression time. The benchmarking was conducted on x86 configurations using the x86 TSC (Time Stamp Counter). In the end, they realized that LZ4 is the best compression/decompression method for Ubuntu 19.10 (Eoan Ermine) as BZIP2, LZMA, and XZ were slow to decompress, while LZ4 was over seven times faster than GZIP. On the other hand, LZO was about 1.25 times faster then GZIP, but not fast enough.
Next major version of Ubuntu is going to be ...FAST.