What is a reasonable amount of time? A 2" marble on a Lynx isn't going to be lickety split, whether you're on a tank or concentrator. If you're looking for faster speeds on large masses of glass, you need to be looking at a 2 stage torch.
If you add a holding tank to your setup, your Lynx will perform much better:
http://web.archive.org/web/200806101...ktutorial.html