Hi Declan,
Virus scanners can slow things down significantly on Windows, including virus scanners can go into overdrive if you are touching many files, touching files with atypical extensions, or building and then immediately executing a new binary.
To start, you could try temporarily disabling your virus scanner and see if it helps.
If it does help, you might be able to benefit from finer grain changes. Most virus scanners support exclusion lists if you have sufficient privileges. You could try for example excluding (1) the directories with your Go code, (2) the directory shown in 'go env GOCACHE', (3) possibly the directory shown in 'go env GOMODCACHE', and possibly others.
I would be curious to hear your results.
Even if this is not the particular problem you hit, it is something other gophers hit, and it would be nice to document this somewhere if it isn't already.
Separately, I thought that Rust for example would add some default exclusions for Windows Defender, which could be an option for the Go Windows installer. However, I'm not seeing that just now based on some quick spot checking, so maybe that's something Rust only used to do, or perhaps I am thinking of something else.
Finally, especially if you are in a corporate environment, there can be other security agents, network services, proxies, and other agents that can interfere with development performance beyond virus scanners.
Regards,
thepudds