I also agree that py4web would give much better performance.
Web2py is easy so i dont think your friend will face much problem converting the application to web2py.
I have converted an app I wrote in flask to web2py and was able to do so.
The actual conversion i.e. database, html, css was a breeze, however i spent a whole day on the following;
1. had to create my own menu without using menu.py in models to create the menu
2. used blueprint and had to figure out how to do the same in web2py using the controllers
3. had some issues uploading and retrieving uploaded data in upload folder
NB: The web2py documentation is key when you are faced with any issue.
In conclusion, please do try the conversion, you will learn alot and appreciate web2py.