If it draws "greyed out" and then hangs, click somewhere at the side of the screen (not in the middle). In those cases, it's trying to draw the annoying popup telling you your session has expired, and clicking outside the popup dismisses the popup. Sometimes, though, the popup itself doesn't draw, but it's still waiting for you to dismiss it! It always makes the screen "greyed out" for me when it's in this state, so I recognize it easily.

Other than that, it's the procedures I have to use (logging out and logging back in, clearing cookies for the individual brands, printing out each reservation as I make it instead of going back to My Reservations, etc) to work around various bugs with the website that slow me down, not as much the drawing of the web pages per se.

(I'm always accessing it from Firefox. Dunno if there's a difference in how it behaves speedwise between browsers or not.)