Thanks Both of you @zipit @m_adam ,
Quote: "keep in mind coping data is expensive"
I had the feeling that the very nice example I am building on has some limitations (speed) as you mentioned.
I guess I have to re organice this section (selecting points) and clean up.
My aproach as a beginner is more or less like this.
try get it to work anyhow
try to understand it by cleaning
try to make a compact function so it doesn't break my code everytime i touch it ...
I have an old C++ code as an cheat sheet to get a general idea how a perfomant code could look like (selecting & working just inside one big point object list, as far as I understand it) ,
but at this stage I can't combine them jet hence the different selecting aproach.
Anyway I try to get somethingmore robust ...
Thank you for your time.
mogh