<p>Multithreaded compression is not some magic holy grail. Sure it can make the compression phase faster but it requires considerably more memory and more importantly the compression ratio degrades so for distros it might be a bad choice. Also AFAICT deltarpm requires bit-by-bit equivalent compression everywhere to operate correctly and that's not the case if compression depends on thinks like number of processors on the system.</p>
<p>Point is, anybody considering enabling it needs to consider whether it's an actual win for a particular use-case - there <em>are</em> cases like CI builds where speed can be far more important than compression ratio.</p>

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