grpc/doc/ssl-performance.md

SSL in gRPC and performance

The SSL requirement of gRPC isn't necessarily making it easy to integrate. The HTTP/2 protocol requires ALPN support, which is a fairly new handshake protocol only supported by recent implementations.

As a result, we've tried hard to provide a smooth experience to our users when compiling and distributing gRPC, but this may come at performance costs due to this. More specifically, we will sometime build the SSL library by disabling assembly code, which can impact performances by an order of magnitude when processing encrypted streams.

Build system	Condition	Platform	Uses assembly code
Makefile	with OpenSSL 1.0.2 development files	all	✔️
Makefile	all other cases	all	❌
Bazel		Linux	✔️
Bazel		MacOS	✔️
Bazel		Windows	❌
CMake		Windows	❌
CMake		all others	✔️

In addition, we are shipping packages for language implementations. These packages are source packages, but also have pre-built binaries being distributed. Building packages from source may give a different result in some cases.

Language	From source	Platform	Uses assembly code
Node.JS	n/a	Linux	✔️
Node.JS	n/a	MacOS	✔️
Node.JS	n/a	Windows	❌
Electron	n/a	all	✔️
Ruby	No	all	❌
PHP	Yes	all	Same as the Makefile case from above
PHP	No	all	❌
Python	n/a	all	❌