I'm experimenting with the options of the Advanced Conditions. In a certain setting BTT needs constantly between 20% and 40% of the CPU. Normally it is less than 5 %. I don't feel any slowdown of my mac, but when is the CPU usage of BTT too high?
advanced conditions during normal use (not during setup) are only evaluated when the gesture or shortcut is triggered. This means they do not increase CPU usage.
However e.g. if the configuration window is open, they are evaluated constantly (to show the values and to show the green text). This takes a lot of CPU.
Yes, that is the case 
BTT moves my mouse. When the spacebar is down, to the menubar and when it is up again, away from the menubar. While writing you need the spacebar all the time, so BTT works all the time too.
BTT does this well, but needs a lot of CPU. The question is: Is that a problem?
What kind of conditions are you using there?
Before you call me crazy, this is a test, ok, just a test. 
I have put this on: If the mouse is anywhere, then an "a" = "a". But if the mouse is over the menubar "a" triggers a different action. I could move the mouse to the menubar by hand. But what for, when BTT can do it for me? And much easier and faster. Whenever the spacebar is pressed and held, the mouse is on the menubar and stays there. Now "a" does something else. Space+a. When the spacebar is released, the letter is the letter again. This is similar to other shortcuts, cmd+a..... In this case the position of the mouse is the "modifier", space up/down is only needed to activate the modifier, move the mouse.
So far this works fine 
. But BTT is working all the time and this needs CPU 
Do you think that's a problem?
It would be a problem for me because higher CPU usage means less hours on battery and in general higher power consumption 
However I'm not sure whether I fully understood your setup. Are you using trigger on down / trigger on up for the space key and have the save/restore mouse position action assigned?
Correct. It works, but is over engineered.
After several tests I came to the conclusion that the "reverse" short/long press method with a single key trigger is the best. Are you aware of how well this works? By reversing (short press on key down), there are no letter twists in normal writing. This disadvantage has made the single key trigger function unusable for many. I don't know if you want to make it „more perfect“, but everything I put on in reverse works reliably, both actions. This is a feature. Only BTT can do that. I would include this in the documentation.
You probably didn't read this because you are supposed to read so much.
I did see the post & email, but both kids have been sick the last two weeks and I didn’t get to fully understand it yet
I’ll have a look later this week!
If there is anything that i should make more obvious for this feature, please let me know.