While Python Ruby, etc. are not high performance languages, they are commonly used because of their ease-of-writing code abilities. However, in some cases, we may want all 3 attributes - completeness, productivity and high performance. Is there a way to make languages such as Python have performance as high as C/C++? *I know there are a lot of libraries but is the performance ever equivalent to C/C++...

I think the motivation behind this slide in context of the lecture is to illustrate the importance of sacrificing some completeness in order to performant AND productive. Additionally, it stresses on the difficulty of coming up with the ideal/magical language that achieves all three characteristics. Maybe giving up some completeness (and developing domain-specific languages) is the first step towards gaining the knowledge required to create the ideal/magical language.

C++ is a language providing the so-called zero-cost abstraction, which leads to high performance/completeness and but also poor productivity.