Mac mini M2 Pro sluggish in comparison to my mid-2015 MB Pro. What up wit dat?

You might use the Activity Monitor app to see what app(s) or process is keeping the CPU busy during your use of the new mini. With that info you may find a way past the issue.

Please see:Activity Monitor User Guide for Mac - Apple Support

Also, I know that Spotlight needs to do certain chores from time to time such as indexing the drive and its files, and that does use system resources.

Likewise with Photos as it indexes and works on your photo library. If the library is large then that process can take an extended time.

If you cannot determine the cause of the issue within a fe days, then maybe returning or exchanging the mini is an option. If you purchased your Mac directly from Apple, then you have a 14-day window in which to return it without question. If you bought elsewhere, then check with the seller to know their return policy.

Please see: Returns & Refunds - Shopping Help - Apple

Good catch regarding the hub. This is not uncommon.

Goto system prefs on M2 and look for spotlight. Remove drives from there temporarily and then see if problem goes away.

As DI Johnson said, spotlight indexing can be an issue, and is shown in top right corner of menu bar. Look very carefully for a dot in the center of the spy glass icon. This indicates spotlight indexing is going on.

It can also be seen via Activity Monitor as stated by DI, by selecting cpu tab and then look for media analysis and photo analysis. For a new system, depending on the amount of user data that is being indexed and analyzed can take sometime. Hours and sometime days.

another simple check is too create a brand new standard user account, and then log out of your account and into to new baseline account. Does it occur there, if not it’s pointing to something under your user account.

Even an old print job hung in the queue can cause an issue such as this as well. Check the print monitor for something in queue, and delete or pause. Now does that help?