Speed up a sluggish iPhone

Speed up a sluggish iPhone

 

It's widely known that computing devices tend to slow down over time, as components wear out, storage and memory fill up with old files and forgotten apps, and new software is increasingly designed for newer and faster processors.
This is in some ways inevitable, and nothing lasts for ever - certainly not in the world of technology. But you can put off the inevitable by following some simple best practices.
From time to time you should power off your device completely, which clears out the memory. You should get into the habit of deleting apps and files you don't use (photos are a common issue for storage) and archive the latter in cloud and/or local backup. And it's worth going through the settings and checking which apps refresh in the background, thereby using up precious processing power.
More of these tips can be found in How to speed up a slow iPhone.
Note that updating iOS has historically been a mixed blessing in this regard - but that may be about to change.
If your phone is up to it, getting the latest version of iOS is normally great, because it brings patches and tweaks that will help things run more smoothly (as well as some cool new features). The problem comes when your device is only just fast enough to be rated as compatible, because the aforementioned cool features are likely to be big drains on the processor.
But iOS 12 - which has a few cool features of its own - appears to have focused most of all on performance. Apple says it will actually make older devices faster, and while we'd like to see that for ourselves (at time of writing it's still in beta), it sounds great.