There's no such thing as JIT in Go. "go run" builds to a temporary file and executes it. If "go run" is slow, then likely "go build" is slow too. Examples of what takes a long time to compile would probably be good information.

Perhaps you have go-pie installed and that's the cause.

Sorry about the misleading title - I'm new to go. Indeed, building the code is slow, too:

$ time go build webserver/main.go
real 0m17.610s
user 0m22.847s
sys 0m0.770s

Building hello-world is very fast, though:

$ time go build main.go
real 0m0.102s
user 0m0.105s
sys 0m0.019s

Here are my installed versions:

$ pacman -Q | egrep '^go |^gcc |^clang '
clang 5.0.1-2
gcc 7.2.1+20180116-1
go 2:1.9.3-1

I do not have "go-pie" installed.

I can try to install an older compiler and check the difference if that would help. I had hoped to hear you say something like "Oh yeah, everybody's hitting that issue right now, hang on for a fix." Since you're not saying that, I'm inclined to think maybe something else changed on my side besides the compiler update.