Yup! Many do. Github just wrote about it here (replacing the Rails default HTML escaper with a C one for a 30% increase): https://github.com/blog/1475-escape-ve

Yup! Many do. Github just wrote about it here (replacing the Rails default HTML escaper with a C one for a 30% increase): https://github.com/blog/1475-escape-velocity https://github.com/blog/1475-escape-velocity and I think the Judy Arrays they're using for code classification are in C. At my job after benchmarking we've done things like break out computation heavy things into C/C++, and have been even eyeballing things like Go and the Lua/Nginx based OpenResty for small computationally heavy services. In many cases this means rewriting what used to be a 3rd party library. The big question is usually around cost in time and if we want to have to maintain that knowledge for the long term. Most of the time it's cheaper to toss more servers at it - but for certain things - namely cases where latency is very important no amount of scaling out is going to make it faster.