a 4 year old workstation/HEDT that was widely viewed as being an out-of-band excellent performer for its time, and the laptop is outperforming it in multithreaded performance by almost a factor of 2, with half the (performance) cores, with no SMT.

yeah, that actually is fairly wild. Granted, there are good technical reasons there (lower memory bandwidth, the 1950X having a NUMA/NUCA arrangement that often hampers the ability to bring all the cores to bear on a single task, Zen1 having extremely high memory latency and cross-CCX latency in general, etc) but it still actually is a very impressive feat.