improve high compression ratio for file like #3793

improve high compression ratio for file like #3793

this works great for 32-bit arrays,
notably the synthetic ones, with extreme regularity,
unfortunately, it's not universal,
and in some cases, it's a loss.
Crucially, on average, it's a loss on silesia.
The most negatively impacted file is x-ray.
It deserves an investigation before suggesting it as an evolution.