The very fact that this 11 page thread (and there are many threads on this topic) has remained at the top of the forum for so long suggests that this a real issue. It doesn't sound like everyone -- or perhaps even most people -- have been affected due to how they use their iPhone however.
I was on the fence about getting an iPhone 6 or 6+ but now I think I *may* skip this upgrade.
It is only because it is the same old same old people complaining about it, not just in this thread or other specific ones, but at every other opportunity spoil it. Just a few making a lot of boring noise.
As I said before I don't disbelieve them that they are experiencing that, however there can be so many factors involved which keeps on getting ignored. It works fine for the millions of other people who don't take to the forum and complain about it in every thread. It's getting rather tiresome and boring now.
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Yawn. I never questioned speed, and staying within Safari whilst flicking between a few tabs will usually cause no reloading. The issue happens when you switch between Safari and say the Ebay or Amazon apps, where you have a search loaded up. If you then switch back to a Safari tab after using the app for a bit it will reload, as will the Ebay/Amazon app when you go back to it after spending a bit of time in Safari! Why pointing out an obvious and highly detrimental flaw is considered 'trolling' is beyond me, and if I'm 'delusional' for pointing out what is quite obviously a massive flaw then call me a medic because I must need some medication (or Apple KoolAid).
As I confirmed yesterday, I've done exactly that test and just can't replicate what you are experiencing. So let's assume we are both correctly expressing our experience, then only one conclusion can be drawn which is that it isn't an inherent problem.