while waiting for a complex part to regenerate, I 've got some time to write this text.
In January 2006 Intel introduced its "Core Duo". I think this was the first (consumer) processor with more than one core per socket. The multi-core race of the last years gave us cpus with core counts up to 64 cores (e.g. AMD Threadripper).
In the meantime (about 16 years) PTC decided to keep its flag ship CAD - Software single threaded.
My request for Creo is to get finally some benefit of multi-core cpus.
Until then, I watch Creo being stuck at about 6% CPU utilization on my 16 Core machine.
There is an existing product idea for this. Please go vote for it.
The official answer from PTC (so far) is on page two:
There are some aspects of Creo that are multi-threaded: shaded image generation and NC toolpath generation come to mind.
With any hierarchical feature based modeller, how do you do multithreading when each feature is built on the prior feature? You cannot just regenerate feature 202 without regenerating features 1-201 first. (Well, PTC does use markers, so Creo can actually do that, but that is different.)
Creo isn't exclusively "single threaded". Over the years PTC has added support for multi-threading where it could do so.
Of course we all wish they would do more and do it quicker. My customers all want me to make my products lighter with increased functionality...sometimes I can accomodate, sometimes I can't.