Mobile rendering speed test: some suggestions

[neteler]

Google offers a rendering speed test (mobile and desktop):

https://developers.google.com/speed/pagespeed/insights/?url=https%3A%2F%2Fstaging.grass.osgeo.org%2F&tab=mobile&hl=en

While desktop looks quite good they suggest to improve some issues on mobile devices:

[...]

... maybe some low hanging fruits there?