I have created a child theme and, if I do not understand, if I want to modify the code included in php files, I have to copy the files from the parent theme to the child. If this is so, I foresee that in the end I will end up with almost all the php files of the father copied in the son.
1-Is there an alternative to this for which I do not have to do this copying of files? Any plugin?
2- Does it really hurt to have the php copied in the performance of the web?
3- And for the js files; What options are there?
Thanks