You probably have some conditioning that discourages use of '-9', but that's generally totally fine to use with zstd in terms of speed. I've been a zstd conver

You probably have some conditioning that discourages use of '-9', but that's generally totally fine to use with zstd in terms of speed. I've been a zstd convert for a few years now and haven't settled on any particular ideal setting. Sometimes the very high compression levels (-19) produce a worse result, sometimes they kill it. I think most of the time I'm using -9. I've seen cases where '--ultra --long -22' was bringing size down by 10% or more compared to the normal settings, and also cases where changing the defaults at all produced significantly lower compression.