Use Python Framework or Build Own
Learn from existing frameworks, I think. The Python web stack (wsgi, sqlalchemy, template engines, full stack frameworks, microframeworks) has spent a lot of time maturing. You'll have the opportunity to develop fast and learn from existing design.
I am an experienced PHP developer (10 years) who has built 3 different custom frameworks for extreme high traffic sites. I have recently started to get into programming a lot of python, usually just for fun (algorithms). I am starting to develop a new site as my side project and wanted to know if I should use a pre-existing python web framework (Django, Pyramids, ect...) or develop my own.
I know things might go a lot faster using a pre-existing framework, but from my experience with PHP frameworks and knowing the amount of traffic my side project could generate, whould it be better to develop an extremely light weight framework myself just like I have been doing for a while with PHP? It also might be a good way for me to learn python web development because most of my experience with the language has been for coding algorithms.
If I do use a pre-existing framework I was going to try out Pyramid or Django.
Also do other companies that use Python for web development and expect high traffic use their own web frameworks or a pre-existing one?