Here's an interesting thing for those of you with erratic and/or slow wifi.
Go to browsermark 2.0 and run the test on wifi. Good chance you'll score poorly, in the 1450-1850 range, when a properly working IP5 should be in the 2600 range.
Then turn wifi off. Run the test with cellular, don't even use LTE, just good old slower 3/4G, and amazingly, your score will likely be much better than the wifi score. Further proof there's a wifi problem with some 5's.
I ran BM on my pretty quick 33-34 Mbps, 15 ms ping time, home network, and got poor scores, in the 1500 range, the software kindly tells me 80% of phone browsers are faster than mine.
Then I run it on my att 4g (NOT LTE) connection, amazingly, I get 2600+, and this is on a 3-5 Mbps connection, with 100 ms ping times! So, my wifi, which is 10 times faster, is WAY slower at actual rendering and data throughput than my far slower cellular connection.
Oddly, when it's working, my 5 will score good times on speedtest, and it'll load pages very fast as long as they're mobile pages or pages without heavy content. But when asked to render a large photo, or load a page with lots of content to be downloaded, it's slow as can be. It'll score 33 Mbps on a speedtest but then seem like dial up rendering a 1 MB photo. My cellular connection at a mere 3-5 Mbps is way faster at downloading anything significant. My 4s will download most files/photos much faster, even though it scores slightly slower in a speedtest, the reason being, the wifi chip/antenna in the 4s works, and the wifi in my 5 doesn't.
I too will wait another month or 2 to let Apple figure out the problem, then get a new phone.