It's not the game, it's your set-up. My guess would be your connection's lag time (bandwidth and ping). With every click, the game client contacts the server, and then waits for a reply, before you can click again. That creates a short delay for most, but normally a lot closer to 0.5 seconds than 0.5 minutes.
If you have a wireless router, it's the obvious suspect. Try rebooting it. Check if there are any unauthorized users logged in. Check for interference. Try moving the router (or the computer). Check if you're getting the bandwidth you're paying for, and decent ping times (there are Web sites for this). If you've made any changes to your system lately, especially relating to the Internet connection, undo them.
Insufficient available CPU or memory can also slow things down dramatically. If your connection, CPU, and memory are at a level that should be sufficient, then there's something that's eating the resources on your computer. If you're running a lot of programs in the background, try shutting them down, including non-essential programs that load automatically. A lot of people have a lot of that dragging their computer down. Any recently installed programs, or updates, are prime suspects, most especially if they connect to the Internet. Check if they load automatically, and if there are new updates, which may contain fixes to a problem. Try shutting them down, rolling back updates, or simply uninstalling them.