Python, IMHO, has a great collection of modules/frameworks for web application development (WTForms, SQLAlchemy, Jinja2, etc) so I'd prefer to have the "rendering/logic part" of the web application written in it. The performance challenges can be overcome by hooking up Python to "workers" written in Go, for instance, using Zeromq.
However I would have liked to take advantage of Tornado's asynchronous requests handling thus my disappointment with its performance in the said benchmarks. I wanted to avoid using "uwsgi" with Flask because of an already complex technology stack i.e: Nginx + uwsgi + Flask + zeromq + Go + sql/nosql database(s)
Perhaps the question should be, "Why are you even that worried about performance?" Instagram and Pinterest, two extremely high-traffic sites, run on Python. And as always, a little caching goes a long way.
Why are you even using Python if you are worried about performance?