Fast Blur - is an extension, which blurs the whole screen, by using an algorithm, which's a bit tricky. So, the main feature is, that script copies view content into another view(which is smaller than main view), and then turns it into a surface. A final result is a sprite, which was created by using sprite_create_from_surface().
Attention: This script shows great results on mobile only if you are using blurStrength > 50 and blur rarely(at least once in a 20-30 steps).
In order to understand the principle of work, I advise you to look into the project or ask a question here ;)