Restart Your iPhone
Restarting your iPhone is the easiest and most common way of getting rid of any bugs. Why? Because it actually works. And it’s especially useful when your iPhone is running slow.
Restarting your iPhone will clear up any potential problems or background activities that could be causing it to slow down. The more free memory your iPhone has, the faster it should run.
How you restart your iPhone will depend on the model you have. If you have an iPhone with Face ID, you’ll need to press and hold the side button and one of the volume bottoms at the same time. For iPhones with Touch ID, you’ll only need to press and hold the side button for a few moments.
Next, swipe the turn-off slider to the right and give your iPhone a couple of seconds to turn itself off. Then, wait another 30 seconds and turn your iPhone back on. This should fix the issue.