Why will it be slow? The variable is stored in your PC's memory, which is accessed quickly compared to the text file method, which is stored on your hard disk drive, especially if you store a mass amount of data in it. The only advantage of using a socket is, you don't have to store the file in your hard drive, saving some space. But nothing is perfect, as the socket can fail if aha-irc.net goes down for any reason. These days, modern computers come with an ample amount of RAM and hard drive space, the speed issue shouldn't be a major issue to fuss over.
P.S. You can see FordLawnmower is updating his socket scripts every once in a while on account of site source code changes and all that. A socket script requires maintenance and that's the price one has to pay if you choose to use it.