ZRAM creates a block device in RAM where pages that would otherwise be written to swap (disk/SSD) are instead first compressed, then stored. This allows for a much faster I/O of swap, and also, the data compression provides a significant amount of memory savings.
https://haydenjames.io/linux-performance-almost-always-add-swap-space/
https://haydenjames.io/linux-performance-almost-always-add-swap-part2-zram/
