With Go: every release. Free performance improvements and backwards compatibility. It also doesn't require anything installed on the server, so it's just updating a ci script.
They eliminated re-scanning of the stack on Go 1.7 by adding a hybrid write barrier which is 90's work (found the proposal: https://github.com/golang/proposal/blob/master/design/17503-...). So Go is by no means state-of-the-art performance wise. That is not bad and has its benefits, one of them being that you can improve with every release.
Yet Go is blazingly fast compared to most other languages that are widely used for web server development (except, maybe, Java).
It seems, given the end of Moore's "Law", as well as environmental concerns, that language efficiency will get more attention. It'll be interesting to see if languages like Swift, Rust, and Julia can gain traction for web development.
I wonder how uptake has been for IBM Kitura so far...
That being said we still use mostly Python 2 for our Python services.
It's a lot easier of a transition than it used to be. Any other support replacement language would of course also work to keep you secure, but honestly might be more transition work.
If you're a low-value target running unimportant stuff on an airgapped machine, this might not matter.