Being a programmer you probably know this already
@PaoloBLEvo but I'll suggest it in case it's helpful anyway as I like programming problems
It might be worth trying to damp the displayed value a bit so it changes more slowly - trying a simple damp like this:
new value to display = old value to display * (1-X) + new actual value * X
where for example X = 0.1 (or adjust this according to how fast you want the value to change)
You could either feed in your average from the last 2 seconds, or feed in the direct value however fast you are sampling it.
You could also try only displaying a new value if more than a certain time has passed (2-5 seconds?) or if the value has changed by more than a certain percent (5%?). So that would handle fast changes and possibly be more stable when not changing a lot.