How to keep 2017 Macbook Pro / Mojave from slowing down when not on A/C power? All of the guides that I have found are out of date.

My model identifier is "MacBookPro14,3".

One such example of "slowing down" is that when the MacBook Pro am plugged in, the application iTerm, is very fast. Whereas, when unplugged, there is a noticeable delay for every character typed. This is partially due to the use of oh-my-zsh and it's various plugins. But, the difference is night and day when plugged in or not.
It looks like the specific issue that I was having in iTerm is solved by an option in the iTerm preferences to not use the GPU renderer when on battery. It can be manually turned off.