OT, but how does this work? Why does it improve rendering? Is it downloading both the normal and bold weight rather than only one leaving the browser to do the rest?
>Is it downloading both the normal and bold weight rather than only one leaving the browser to do the rest?
Yes. The original URL only provides the normal weight (400), but you can specify other weights/styles[1]. 700 is the weight for bold and GP's URL requests both 400 and 700.