If you are writing very performance critical code, you shouldn't write in Python anyway. You chose Python because ease of development is more important than raw performance.
The overhead of function calls and property access in Python is part of the price for the increased flexibility of the language.
Rossums tips are for the corner case where you want to improve performance but you don't bother rewriting in C, e.g. if you have a small bottleneck in a larger program.
There are few applications that require 100% of the code to be high performance. Most performance problems are of the "bottleneck" kind, so writing your entire app in a language like Python for that ease of development is smart. It gives you options to optimize that 1-2% of your code that is critical without incurring a development penalty on the other 98-99%.
GVR's tips can be seen as an escalation path for optimizing. Don't jump into C before you've actually optimized your Python, because you might not need to.
In 10 years of writing Python, I've yet to hit a point where I've needed to do that. I'm kind of looking forward to it, actually.
The overhead of function calls and property access in Python is part of the price for the increased flexibility of the language.
Rossums tips are for the corner case where you want to improve performance but you don't bother rewriting in C, e.g. if you have a small bottleneck in a larger program.