Hello,
in only one of my project I've a very annoying bahaviour. Every few seconds the interface hangs and on the status bar at bottom I read "scanning project (<project_name>) for parsing, mode=0"
It seems to happen mostly after I save the file and/or when I do autocompletion, but happens when just writing code too.

I've tried cleaning the includes and rescanning them. I use build 17030

Thank you

Scan is initiated by file system change notifications. So there is something -- either file or folder, that changes frequently. You need to figure that out and stop this activity.
Also you may want to switch to v18. It re-scans the projects in background and it is doing so in a much less disruptive way.