[a_t48]

zstd has higher level modes. Default is -3. I saw a good tradeoff between compression speed and ratio up to -9 or so. From -20 to -22 it will use much more memory and IIRC can have downstream effects on decompression speed. I'm using -9 for my container registry and plan to recompress at a higher level for commonly accessed base layers, as well as give customers a button that lets them pay a bit more to do it themselves.

[loeg]

To be a little pedantic, the usual zstd levels are positive integers (1-22 default 3). The negative integers denote "fast" modes with worse compression (there are only a few of these).

[edflsafoiewq]

I think those are CLI options, not negative signs. Ie. you call zstd -3 for compression level 3.

[a_t48]

Whoops! You're right, and it's too late to edit.

[chickenbig]

Even compression level 1 or 2 is pretty good.

I once used https://github.com/google/riegeli and a low zstd compression level to store large quantities of protobuf data in an efficient manner (in terms of CPU, RAM and streaming to disk). Shame Riegeli is not well known, not well documented and does not have many tests.