Is there a difference in performance between a the default scaling option and selecting a resolution?
Changing your resolution doesn't really affect performance.  What will give the effect of improving or reducing performance is refresh rate.  A higher refresh rate will smooth things out giving you the &quot;feeling&quot; that things are much faster.  A lower one will make things look more &quot;jumpy&quot; thus giving the effect of lagging performance.
The default scaling is what macOS has determined to be the &quot;best&quot; optically for your particular setup.