But Mercurial was written in Python and performance is comparable to git. So, his argument is not correct about the performance reason on choice of C over C++.

But Mercurial was written in Python and performance is comparable to git. So, his argument is not correct about the performance reason on choice of C over C++. Even interpreted Python which was used in Mercurial was not speed bottleneck. Yes, I know that most of speed critical sections was written in C. But almost all project in Python. Also Darcs was written in Haskell and Bazaar with Python. I hate C++ too (over 10 years of experience). But Linus is full of BS too. Yes, choice of C language in Git is right choice. But source code of Git is horrible and unmaintainable mess.