Maybe. This means that the performance bottleneck is the database. Does this justify the use of a slower framework ? I don't think so. I'll use an SQL db and C

Maybe. This means that the performance bottleneck is the database. Does this justify the use of a slower framework ? I don't think so. I'll use an SQL db and CPython for the MVP, but I have an open road in front of me to optimize with NoSQL, PyPy, wherever it is required. Note that there are many other parameters to consider, like ease of programming, toolbox richness, reliability of code, etc. The choice is up to you according to your weighting of theses parameters.