JWZ told a similar story about Netscape between versions 3 and 4 being rewritten in C++. The full story is in the book Coders at Work, but part of it appears here:

https://gigamonkeys.wordpress.com/2009/09/28/a-tale-of-two-r...

Of course this was mid-90s when both the language and especially the compilers were quite different from now (and the compilers very buggy indeed).