Would Protoype and CI be slow?

[eluser]Michael Wales[/eluser]
Any framework (whether it be PHP, Javascript, Ruby, Python) is going to decrease performance. You have to make a call as to whether the degradation in performance makes up for your ability to develop in that particular environment.

Both CodeIgniter and Prototype (although I prefer jQuery) are superior frameworks for their languages with amazing performance. Time and time again these frameworks dominate their competitors in benchmarks. I don't think you have anything to worry about.