I have been using pyramid for years now as our main application server and we are very happy about its performance. We use several python web frameworks (flask, tornado) together with sqlalchemy. It has proven itself over many projects. So far there was nothing really bad you could say about pyramid. Sometimes when you start your development process of new project pyramid takes some time to load all modules again but this behavior should not surprise you if you know how pyramids work. Try pyramid out! You will like it. Performance issues solved by pyramid.