I'm running a heavy duty number crunching app on my MBP, and it can take days to run. I've noticed that if there's no user activity on the computer, the processor appears to goes into slow mode, which I don't want. Each iteration of the calculation takes roughly the same amount of time, and after each iteration, it updates the display with the elapsed time. When I check the last completed iteration first thing in the morning, it's obvious that the processor has been idling overnight, or has possibly even gone to sleep. (I have preferences set so that it's not supposed to go to sleep, as long as it's not running on batteries.)

Is there any way to make sure the CPU is always running at maximum speed?

I've run across apps that jiggle your cursor periodically to keep your Mac thinking that there's someone at the controls; I wonder if something like that would help? (Sorry, but I can't think of either an app or even a good search term at the moment.)

How about these Utilities from the Mac App Store (they appear to be free and well regarded)...

Anti Sleep or Amphetamine

Jiggler is the one I had in mind, and Caffeine, which I just remembered, works along the same lines.

What the hey, they're all free!

I was also using Caffeine, but I believe the developer is no longer supporting; so, it's long in the tooth without an update. ...As result and for grins, since it was one of my suggestions, I've deleted Caffeine, which worked Ok, and I'm now test driving Amphetamine as it's previous update was last September (the other suggestion was last updated in 2015).

I'm not running any of the above-named apps (utilities?); I just follow MacUpdate on a daily basis, and I've got a stockpile of items that I've either bookmarked or remembered against future need.

Despite the lack of developer interest, Caffeine is reported to still be working in Sierra, and in Bob_00001's circumstances, anything that may work is worth trying.

Thanks for the suggestions.

I just downloaded Amphetamine from the app store. It appeared to have the highest rating. I'll see how it works tonight.

I'm curious about whether Amphetamine works for you; it's not at all in the same vein as either Jiggler or Caffeine, which are "mechanical", as opposed to Amphetamine's command line functionality.

I let it run overnight last night, and as far as I can tell, it worked fine. I'll know for sure after a few days, because there's occasionally a situation in my app that causes a significantly different elapsed time for some iterations.

Amphetamine has a lot of bells and whistles that you can configure in order to turn it on or off automatically with various triggers or a time schedule. I didn't bother trying to set up any of that. I just manually turned it on.