I looked up some cookie clicker threads on random other forums, and there were some ridiculous pics, like some person who said it eventually has to use scientific notation when you have heaps and heaps of time machines. (You can cheat easily though since it's javascript, to be fair.) I'm impressed by how well this game scales.
I find the best method for this game is to click the cookie 15 times, and let the cursors and bonuses you buy do the work, sit back and relax, and buy shit like every 5 minutes or so.
Once you break the portal threshold, you are in the money basically, not later after that you are buying crazy amounts of time machines and portals and breaking the space time fabric.
I think I got one of those achievements yesterday. I beat the clicking world record, but I think the game thinks it's because I cheated :(
(I did cheat, using a usb mouse + my laptop touchpad for double clicking power, but that's not the point)