Is OOP always significantly slower than procedural?
Back when I was working on Smalltalk at ParcPlace, we had a saying about Smalltalk that can also be applied to using Objects with Perl:
Smalltalk: A little slower, but a lot sooner.
The point being that the leverage gained from having a well tested class hierarchy (think CPAN) to build on usually wins out over the perceived need to make the code as fast as possible.
Method invocation is 15-20% slower than static function invocation, but performance bottlenecks tend to cluster into small sections of code, allowing selective optimization. If you're up to speed on objects, you'll get to the bottlenecks quicker, and will have more time to profile and optimize.
