Ever since I got the iphone 5 I have had dreadful wifi speeds at home, but only when downloading from the App Store. The Speedtest app always showed fast results, however. Last night I noticed that my router was using googles DNS servers (22.214.171.124, 126.96.36.199) which is a change I made a year ago without any issues. I then went back to using my default ISP DNS settings and I now have great speeds when downloading from the App store. I don't want to get into conspiracy issues, but others with this problem may want to see if this helps.