When use the interactive smooth on pencil tool, there is a problem because is based in LPE simplify, so it retain original path, and, because is not smoothed, using original path become complex because a lot of nodes.
The goal is add a parameter in pencil tool inkscape preferences to specify a base simplify of interactive pencil draws. If the slider simplify increase this amount, the original path is simplified to the preferences amount. So the path still has the simplify interactive but with simplified amount of nodes as base path.
Sorry because my english seems to me complex to explain well.
I have a patch working.
It add a pencil tool inkscape preferences option with a default of 25
If the slider is less than the preferences value, use the slider value instead.
Please check using it, is more easy to undertand.
This add the feature I try to explain