The major version bump is for some incompatible changes, though they are unlikely to cause trouble.

keyword arguments to psort besides :key have been replaced with a single :granularity argument; the old arguments are now ignored

besides have been replaced with a single argument; the old arguments are now ignored removed deprecated aliases from 1.2.0 and 1.3.0 (you may not be aware of them since they haven’t been listed in the documentation)

A function defined with defpun is now optimized for N worker threads where N is the number of cores. The old behavior is available with defpun* , which defines a function that is optimized for N-1 workers (and has less overhead).

is now optimized for N worker threads where N is the number of cores. The old behavior is available with , which defines a function that is optimized for N-1 workers (and has less overhead). added psort* — like psort but targets N-1 workers

— like but targets N-1 workers improved performance of psort

task categories are now compared with eql ; same for ptree node ids

The benchmarks page has been updated to reflect recent optimizations, which includes optimizations in SBCL itself.