As of 9/3 we have a new version of Project Quick Graphics Viewer version 18.104.22.1684761.
My first experiences using it are not good. Within 5 minutes is was getting 2 or 3 FPS and going Not Responding. Memory use wasn’t all that high, 1.3gb. But, using System Explorer (free program) and clearing memory still helps.
The main viewer, Second Life 3.8.3 (304115), ran much better. So, unless you are wanting to play with the Graphics Settings feature or Complexity Settings, you may want to wait a couple of weeks before you try it.