Absolutely wonderful picture! I am VERY impressed! I have found that I must be very careful with glass, especially when two panes of glass overlap. I see that your bus stop uses glass just like the "real thing". I'd suggest that you break up the glass panes (which is a pain!) to avoid the overlap. If this is a still image, you can get away with that, unless you change your camera angle. The second suggestion is to fuss with the glass materials. Some of them are really render hungry. One silly trick is to take the "simple" white material and fuss with it, adding transparency, specularity and reflection to it to "fake" the glass. That might help if you can live with the look. Of course, you know to make sure that the bump height is zero, and to turn off all settings that aren't needed. You might also check for reflection. If you can pull that lower, the render will speed up. Finally, and this may seem obvious, you aren't using the glass as a volume? Volumetric material is mega slow (at least i have found it so). Hope this helps give you ideas. Great picture! Good luck!