Rob Pegoraro, Special for USA TODAY
Q: Ever since I downloaded iOS 7 onto my iPhone 4, typing has become very slow. Any solutions coming out for that?
A: First off, you'll have to forget about reinstalling iOS 6. Whatever you might think of iOS 7, reverting to its predecessor vanished as an option days after 7's debut last month, when Apple stopped digitally signing older versions.
What you can do, however, is try to ease an older iPhone's burden in the new operating system. Apple already turns off most of iOS 7's visual effects on the iPhone 4 to compensate for its reduced graphics power, but you can also try another frequently suggested remedy, stopping iOS 7 from checking for new data on behalf of third-party apps.
To do that, open the Settings app, select "General", tap "Background App Refresh" in the right-hand pane, and touch the switch atop that category.
Leaving enough storage space free is also a good idea. The Settings app will show which apps have eaten up the most space: Open it, select General and tap Usage.
But with a slowdown as severe as the one this reader reports, those intermediate steps might not be enough. Instead, try the traditional computing remedy of reinstalling everything from scratch. Connect the iPhone to a computer running iTunes, do an encrypted backup there, then restore the phone to factory settings; when that completes, you can restore your apps and data from the backup.
Adam Engst, editor of the long-running Mac newsletter TidBITS, suggested a last resort: a clean install of the core system software without any of your add-ons. To do that, you'd do a system restore but hold off on bringing back any old data.
If reading all this has you leery about going ahead with an iOS 7 upgrade on an iPhone 4 - well, maybe you should be. The iPhone 4, which debuted in the summer of 2010 and runs on a relatively slow A4 processor, is the oldest device iOS 7 supports.
Ars Technica's Andrew Cunningham went to the trouble of timing a variety of common tasks on an iPhone 4 before and after upgrading to iOS 7. The results: "Everything is slower in iOS 7, usually by one to one-half second or so but sometimes by more."
Such iOS 7 additions as Control Center, which lets you change such common settings as airplane mode by swiping up from the bottom of the screen, make this a useful upgrade overall. But if I had an iPhone 4, I would hold off on installing 7 and watch to see whether upcoming iOS releases improve 7's responsiveness on older hardware.
The iPad 2, the next-oldest device to get iOS 7 support, is a good nine months newer than the iPhone 4 and runs on the faster A5 chip that later landed in the iPhone 4S and the fifth-generation iPod touch. You should be fine putting iOS 7 on that.
Meanwhile, many Android users never will get the chance to make this decision: Manufacturers and carriers never got around to shipping Google's updates, leaving them stuck with obsolete versions of that operating system.
(A friend thought he'd lucked out when Verizon Wireless and HTC delivered the 4.0 Ice Cream Sandwich version of Android for his HTC ThunderBolt. But the experience of "ICS" on this already-flawed phone was as bad as our iPhone 4-using reader's introduction to iOS 7. A factory reset to the phone didn't speed up things much; he eventually gave up and bought a Galaxy S4.)
Tip: The App Store's "Near Me" category can lend some local flavor
A less-heralded iOS 7 feature offers a little extra help to users away from home: A "Near Me" list of apps that are popular among users around your current location. Select that, and you can get a quick summary of the iOS programs locals use to read the news, cope with traffic, find restaurants and bars, navigate public transit, explore museums and so on.
It's considerably more efficient than typing in App Store searches like, say, "Washington DC transit." And in densely populated neighborhoods, it can yield interesting insights about things like what languages people speak and where they shop.
Rob Pegoraro is a tech writer based out of Washington, D.C. To submit a tech question, e-mail Rob firstname.lastname@example.org. Follow him on Twitter at twitter.com/robpegoraro.