I don't have an m1 yet but have a similar experience with laptops performing extremely poorly compared to desktops (to be expected) but also poorly compared to my older Apple MacBooks. I have a 2015 13" MBP that will perform a compilation task quicker than my 2019 XPS.

The much older CPU in the MBP has a much faster base clock of 2.4GHz vs 1.3GHz in the XPS. What I find frustrating is that the XPS will throttle down to base clocks for any workload sustaining about 10 seconds, even if the temperature is reasonable, e.g. 50C.

In Windows I can work around this a little using ThrottleStop but I'm primarily a Linux user and haven't found a reliable way to bypass Intel's turbo limits with my Ice Lake CPU. Linux also has annoying bugs where the CPU will limit itself to base clock when connected to AC but then turbo up to 4.1GHz when the AC is unplugged, baffling.

Glad to hear about your positive results with m1, it's for sure a purchase I'll be making in 2021.