I mean if performance Vs C++ was a primary concern then you're limiting yourself to quite a small subset of languages, most of which either have a steep learning curve and/or sacrifice security. This doesnt make sense for the majority of developers out there since very few people really need the performance of C++. That's not to say performance doesn't matter but rather Go's performance is more than adequate for most of the applications it is applied to.

To further that point just look at how I've used Go. I've written two FUSE file systems and a UNIX $SHELL in Go and found the performance to be good enough even on my relatively modest dev machine. I've also written log file parsers that can handle gigabytes or records in seconds. I'm happy with that level of performance because for me developer productivety matters a lot more since I have 2 small kids so hobby projects get very little time allocated to them. This means I'd rather prototype code then optimise later rather than spend comparatively longer building a POC that ultimately might never get enough time to see the light of day.

However you will have your own set of requirements which Go might underperform on and those reasons are as important to you as my requirements are to me.

This is why arguing about how some languages are bad or which are the best is about as worthwhile as arguing which colour is the "best".