> Let's see if we can go even faster. Next, we disable compression in the file cache. We will discuss the file cache in more detail a bit later but for now let's just say that by disabling compression we trade temporary disk space usage for speed:

Something is wrong here. Which compression algorithm is being used here and how much has it been tuned? A core hypothesis of the likes of zram is that disk access is so slow (even NVME), that you can often beat it with the bit-rate of decompression.

1. Is something slow like gzip being used?

2. Is the compression effort over-tuned for size? Do some space benchmarks and make sure that you aren't saving a few dozen MB on GBs of data.

zstd, with 1-3 effort (you may even find negative is a overall win), and a trained dictionary (your data does all look identical) is probably a good start.