Golang - go run takes long to execute - performance

Question

I have a little problem, where every time I run 'go run >filename<' after making changes to my problem, it takes many seconds to start executing.
I tried it with a simple program like this:
package main
import "fmt"
func main() {
fmt.Println("Output")
}
And it took about 18 seconds to print out the result.
And ideas on what could cause this problem?
I am on windows by the way.
Thanks in Advance

Answer 1

Found this while experiencing an identical issue with freshly-compiled golang binaries on MacOS (OSX) Catalina.
In short, the OS now scans a new (to it) binary for malware, it usually does it on first start, but I found that it was doing it 3-5 times in a row, after which the binary got whitelisted and started as normal. Obviously, once you make changes to the code and re-compile the scans start happening again. The scan would take upwards of 20 seconds which ruined golangs fast iteration cycle.
Solution for me was as follows:
sudo spctl developer-mode enable-terminal
Then go to Preferences -> Security & Privacy -> Privacy
In the list to the left you will now have "Developer Tools" section, which will have OSX built-in Terminal listed. Check the box to enable it, and/or add anything else you may be using to develop (iTerm, VS Code, etc)
When running binaries from those applications the scans stop and things go back to normal.

Answer 2

$ go run command always complies the code into a temporary binary file and then executes it, every time it is run.
To go around this you could do $ go build -i main.go which will compile dependencies separately as .a files (i'm guessing this is the part that takes the longest because it takes time to build the dependencies) and then execute it with $ ./main, and each execution should be faster that $ go run.
You could also run a $ go get -u ./... to update all your deps and building with the -x flag will show you if the toolchain is finding incompatible versions.
$ go install builds the command in a temporary directory then moves it to $GOPATH/bin so you can execute it without the path $ main.
The last two commands require a rebuild/reinstall if the code has changes.

Answer 3

If anyone still facing this issue on windows. you can fix it in 2 ways. it works 100%.
open virus & threat protection in windows security in settings
way 1:
turn off real-time protection
way 2:
in virus and threat protection settings(click on manage settings) go to exclusions and add the following three folders
C:\Users\anves\AppData\Local\go-build
C:\Users\anves\AppData\Local\Temp
The folder where go is installed.