Severe performance degradation on 2nd Gen iPad after updating to iOS9.x

you can't downgrade in my experience ipad2 is not slower then it became when ios8 was released

Have you tried factory resetting the device? Have you tried disabling a few things such as background app refresh etc?

I can't speak directly to iOS9 on an iPad2 but you are correct in that 4 years is ancient in the computer world. When we bought an iPhone a few years ago I asked about battery longevity. The Apple sales person said, "Oh at least 2 years, by which time you will be wanting a newer model anyway." Sure enough, after 3 years the speakers went out and the battery had noticeably poorer performance.

Vintage and obsolete products - https://support.apple.com/HT201624

I've seen a report that iOS 9.2.1 released yesterday behaves better on older devices, you might give it a shot.

Speed will never be the same especially if you're coming from iOS 7 or older. I have the same experience with a 4th gen iPod Touch. While the latest supported version for my iPod Touch is iOS 6, I refuse to install it because iOS 6 may kill it completely.

The factory reset has help many folks.

R

A disclaimer.

I make no guarantees, expressed or implied, that any of my own procedures will return EVERY older iPad to a usable, running condition.

Try resetting All Settings found in the Settings App under General and in the right column under Reset.

Try resetting histories and deleting/resetting caches in all of the web browsers you use.

If you use Safari, these functions maybe in the Settings App under Safari.

Other web browsers have their settings inside of the running app, itself.

If your iPad has been activated for iCloud, in the Settings App under iCloud, to the right, under iCloud Drive, tap iCloud Drive and make sure Safari is turned off for saving Safari data to iCloud Drive.

Also, under iCloud in the Settings App, in iCloud Drive, disable the saving feature for any other apps that you DO NOT want data being saved automatically to iCloud Drive.

If using Safari is still causing issues,

Try changing/using another, different third party web browser.

I don't use iOS Safari too much any longer because I found it causing me some headaches on certain websites I, regularly, visit.

I commonly use another third party web browser, Perfect Web Browser (there are others that may suit your web browsing style better, so look at all of them first to see which third party browser may work better for you) and I never experience a lot of the issues that Safari was causing.

In the Settings App under the General tab, to the right under Spotlight sesrch, try disabling the search under apps that really do not need a search, like some games, remotes, apps that really do not need to be searched, etc., to reduce the list for Spotlight to search.

Try turning on Reduced Motion.

This is found in the Settings App in the General tab the left panel.

In the right panel look under Accessibility, the look for Reduce Motion and turn this feature "On".

You should see an appreciable performance increase on all iPad 2, 3 and 4 models.

In the Settings App under the General Tab, in the right column, look for Background App Refresh and turn this setting to "off".

If you are willing to do this (I, personally, wouldn't recommend this), some users have reported that turning off Find My Phone/iPad, in Settings App under iCloud, has improved iOS performance, although I don't how this feature could be causing such a performance slowdown, unless its a bug in iOS that is only affecting some iPad users.

Try another hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons.

Good Luck!

If not all of my suggested fixes or possible solutions have completely returned your iPad to acceptable, normal or improved performance,.

Here is my own modified backup/restore procedure that has already worked, successfully, for several iPad 2/3 users, so far!

I have done this and my iPad 2 and 3 are working like new, " out of the box" units!

THIS PROCEDURE DOES NOT RETURN YOUR iPAD TO ITS PREVIOUS iOS VERSION.

Also, as a disclaimer.

I make no guarantees, expressed or implied, that any of my own procedures will return EVERY older iPad to a usable, running condition.

First, connect your iPad to USB and sync and backup your iPad to iTunes (make sure,FIRST, your iTunes is up to the most latest version).

Then disconnect/eject your iPad from the computer.

From just the iPad, in the Settings App under the General setting, look in the right column for Reset option, then erase and reset your iPad to completely erase your iPad and then, again, from the iPad, set it up as a new iPad setup to factory "out of the box" operation.

Then reconnect your iPad to the computer and make sure to cancel the syncing, by tapping the small X to the left in the top center iTunes display box.

iTunes should detect your iPad. If iTunes begins to try and sync, again, cancel the sync.

Select Restore from Backup instead and pick your last backup to restore back to your iPad.

Once the restore is complete, finish setting up the iPad and let it sync back to iTunes you can either cancel the sync, again or let it backup, again.

Then disconnect the iPad.

Do one hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons.

Once your iPad is back to the Home screen,

In the Settings App under the General tab, to the right under Spotlight sesrch, try disabling the search under apps that really do not need a search, like some games, remotes, apps that really do not need to be searched, etc., to reduce the list for Spotlight to search.

Try turning on Reduced Motion.

This is found in the Settings App in the General tab the left panel.

In the right panel look under Accessibility, the look for Reduce Motion and turn this feature "On".

You should see an appreciable performance increase on all iPad 2, 3 and 4 models.

In the Settings App under the General Tab, in the right column, look for Background App Refresh and turn this setting to "off".

If you purchased any music from iTunes, you will need to redownload that content back to your iPad for playing directly from your iPad and not from Apple Music servers.

Also, if your iPad contained a lot of images in the Photos app, these will take time to regenerate the original AND thumbnail images themselves inside of the Photos app when you first launch it.

Good Luck!

How can i reset my device?

Erase all content and settings on your iPhone, iPad, iPod touch, or Apple Watch - Apple Support

Warning: you will lose everything. Backup prior to resetting is highly recommended.