Summarize the following:
Restarting your iPhone completely will reset the system memory. This can fix apps that are misbehaving and eating up too many resources. It can also improve general performance.  Press and hold the Power button until the Power slider appears on the screen. Slide the slider with your finger to turn off your iPhone. After about ten seconds, press and hold the Power button again to turn the iPhone back on. You can use a quick trick to clear out the RAM on your iPhone, giving you more free RAM for apps to use:  Press and hold the Power button until the Power slider appears. Make sure your iPhone is unlocked first. Press and hold the Home button for five seconds when the slider appears. You'll be returned to the Home screen when you're successful. This will clear the RAM that is currently in use. You'll get better performance on your iPhone if you have some free storage space available. One of the easiest ways to free up space is to delete apps that you don't use anymore. This will free up storage space and free up RAM for apps that typically ran in the background. You'll be able to download any of your purchased or free apps again from the App Store.  Find an app on your Home screen that you want to delete. Press and hold the app until it starts to wiggle. Tap the "X" in the corner of the app to delete it. Repeat for any additional apps you want to delete. System apps cannot be deleted. If you take a lot of pictures, they may be clogging up the available free space on your iPhone. When you run out of free space, things slow down quite a bit. The process for transferring pictures varies depending on the computer you're using:  Windows - Connect your iPhone to your computer via USB. Open the Computer/This PC window and right-click your iPhone. Select "Import pictures and videos" to start importing pictures. Click "More options" and then check "Delete files from your device after importing." Follow the prompts to import the pictures to your computer and delete them from your iPhone. Mac - Connect your iPhone to your Mac via USB. Open "Image Capture" and select your iPhone from the list of devices in the left menu. Expand the additional options at the bottom of the menu and select "Delete after Import." Click the "Import all" button to import the pictures to your computer and erase them from your iPhone. Some of the menu transitions in iOS can slow down older iPhone models. Disable these to help improve performance:  Open the Settings app and select "General." Tap "Accessibility." Tap "Reduce Motion" and then toggle "Reduce Motion" on. Return to "Accessibility" and select "Increase Contrast." Toggle "Reduce Transparency" on. Much like your pictures, music files can take up a lot of storage on your device. Removing songs you don't listen to can help improve performance if you're running out of free space. If you purchased the music from iTunes, you'll be able to download it again at any time. If you synced the music from your computer, you can restore it by syncing again.  Open the Settings app and select "General." Tap "Storage & iCloud Usage" and then tap "Manage Storage" in the Storage section. Tap the Music app in the list of apps. Swipe any artist or specific songs from right to left and then tap "Delete." You can also swipe "All Songs" to delete all of your music at once. The iPhone does not have a built-in way to check the amount of RAM that is being used. This is because the system handles RAM allocation in the background, and is not meant to be seen by users. If you want to monitor RAM usage, you'll need an app that will display it. One of the most popular apps is System Status, but you will not be able to see individual apps' RAM usage.

Summary:
Restart your iPhone on a regular basis. Reset your iPhone's RAM. Delete unused apps. Transfer pictures you've taken to your computer. Turn off some effects. Delete music you don't listen to. Use an app to check your RAM usage.