Slow iPhone 6

Hello,

Since updating to iOS11 on my iPhone 6, it has become rather sluggish. Animations are choppy and apps take a long time to load. Of course, I did expect a performance drop upon upgrading, but not one of this severity; it is now slower than my iPhone 5s that is running the same software. I was hoping that that the 11.1 update would resolve these issues, but it has not.

Is this a known issue, or is it specific to my device? Is there a known fix to this problem?

Many thanks,

James