You appear to be the exception.I haven't noticed a lag so far on my iPad 4. Apps start up fast, the news app took maybe three seconds to load content, but hadn't been refreshed in 24 hours. Opening apps happen faster than I can click the icons. Safari seems to be handling tabs better, but I haven't loaded more than four so far.
iOS 6 and 7 were perfect, iOS 8.0 was ok i guess till iOS 8.1.3 came out, it was horrible, system felt slow, doing a simple task like unlocking my iPad 4 i found a lag. iOS 9 saved my iPad 4, its fast and fluid like it did with iOS 7 except for the app switcher lag that doesnt only exist on the iPad 4 but also on iPad mini 2, Air 1, 3rd Gen, when many devices have the same lag, u can say that apple will fix this very soon.Ios 9 on ipad 4 is a lag fest and its real. My iPad 4 performance is dfinitively not like when I bought it with iOS 6. IOS8 was ok, but 9? It lags everywhere. Opening apps is laggy, app manqger is laggy, web browsing is extremely laggy, seriously, I'm the type of guy who don't usualy see lag that much, but the iPad 4 is very, very laggy with iOS 9.
Not really no.... I use FaceTime very rarelyUnless you want to run more recent apps and care about FaceTime