I run Ubuntu on 2017 PC (8700K, 32GB RAM, admittedly, HDD), and it is nowhere near snappy. Boot takes over 2mins until apps actually start to show up, starting new Terminal instance takes over 3sec (if not over 5). Regular programs like VS Code or Firefox are about the same as on Windows.
Software are more bloated than 3 or 5 years ago. Performance with a HDD will suffer as everything has to be loaded to RAM before the CPU runs the code. Put a SSD in this machine and for most tasks your experience will be the same as with a brand new PC.
The beast you mention is even more spec'd than my current main workstation, which has half the RAM, and the entire default install of Ubuntu fits in the cache after boot. The HDD is not to blame; there is something else wrong.
It takes around 2-3 seconds on the first attempt, future launches are instantaneous (cache plus gnome leaves a gnome-terminal-server process floating around).
