As we go on using our gadgets be it phones iPads etc, they get filled up memory wise and tend to slow the device down no matter the RAM of the device.
So here is a couple of ways you can actually speed up your iPads and iPhones

Restart
Restart flushes the memory to help boost performance. To restart your iPad hold down the Sleep/Wake button and use theSlide to Power Off control when it appears. Wait a few seconds and start the device again.
Alternatively you can force reboot the device by holding the Home and Power buttons down until the Apple logo appears onscreen.

Declutter
Get rid of the apps you don’t use. Not only does this free up storage space (important when using a 16GB model) but the tablet should run a little more efficiently if it has free space. Delete unwanted apps by tapping and holding an app icon until all the app icons begin to vibrate, then delete the apps you don’t need by tapping the grey cross before a restart. (NB: You will find yourself unable to delete some Apple-supplied apps).

File management
You should also delete files you don’t need in Settings>General>Storage & iCloud Usage, where you should chooseStorage>Manage Storage. Delete anything you don’t need, after ensuring you have it stored off the device. Now restart.

App refresh
The Background App Refresh feature is useful, but you can tweak a little more performance from your iPad without significantly reducing the usefulness of the device if you switch it off in Settings>General>Background App Refresh, set to Off.

Reduce Transparency: Switch on in Settings>General>Accessibility
Reduce Motion: Switch on in Settings>General>Accessibility

Disable Siri Suggestions:General>Spotlight Suggestions and flip Siri Suggestions to off. If you Siri you can always reenable when you think you might need it and enjoy a faster iPad in the meantime.
Spotlight
How often do you search for things on your iPad? If this is something you do frequently you may want to skip this, but you may see slightly better device performance by disabling Spotlight. (TapSettings>General>Spotlight Search and set Search Results to Off.)

Notifications and Location Services
While they are sometimes useful, Notifications can impact device performance. You should at least review which apps are checking to see if they have a fresh Notification and switch this off for those you don’t need or use. TapSettings>Notifications and go through the list, setting Notifications to Off for all or some of those listed there.
Once you’ve tamed Notifications you need to do the same with Location Services, which you disable in Settings>Privacy.

Year zero
Safari creates a cache of settings and Website data in normal use and this can impact browser performance on your device. To freshen the browser up a little choose Settings>General>Clear History and Website Data to delete the cache, which should improve performance.

Clear RAM
You can apply this in just a few seconds whenever you feel like your iOS device has become a little sluggish. There are two steps:

Hold down the Power button until the ‘Slide to Power Off’ message appears.
Don’t cancel and don’t slide to power off, just keep holding the Power button down and now also depress the Home button for a few seconds.

The screen should flash black before returning to the Home screen.

i,
Slow iOS device may really trouble you a lot. It may stop you from accessing your device. This is very awkward as you cannot use it for your enjoyment or some work. However if you follow some speed up tips for your iOS device then it will be really helpful. In fact I also want to share you how to speedup your iOS 10 when it don't work. Go through the below link and know more about it.
Speed up Slow iPhone and iPads