Can "Discrete only" GPU cause slowness?

Question

I have 2 external monitors to my 2017 Macbook Pro v.10.15.6. Sometimes it slows -- the mouse lags badly.
I installed gfxCardStatus and sometimes the menu choice changes from Dynamic switching to Discrete only. It seems that the mouse starts lagging just when that happens.

Is it possible that "Discrete only" slows the computer?
Why does this switch automatically?
How can I keep it on "Dynamic switching"? The Macbook is always plugged in so power consumption is not a concern.

(This relates to my earlier question, in which "Automatic graphics switching" under Energy saver was getting automatically enabled. I wrote a script to keep it disabled, for better performance with more power consumption. It seems that that is a different setting from this "Dynamic switching" in gfxCard Status since Dynamic switching seems to increase performance.)

Joshua Fox · Answer

The author of gfxCardStatus answered here.

If your goal is better performance regardless of power consumption,
then the solution is really simple: quit gfxCardStatus, delete it, and
disable automatic graphics switching in System Preferences > Energy
Saver. That will cause the discrete GPU to be used all the time.
When gfxCardStatus is running, it manages the automatic graphics
switching setting for you. Dynamic Switching is equivalent to having
the automatic graphics switching checkbox checked.

Can "Discrete only" GPU cause slowness?

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