Q: having updated to iOS 9 all ipads and iphones running very slow any way to backout to ios8

No, downgrading is not possible.

How much free storage space is left on all of these iDevices?

Reloading ios has worked for some.

If you are having problems with apps stalling or crashing,

-- double click on home button

-- swipe up on all the apps to force quit them

Re-boot ipad.

Press and hold the Sleep/Wake button until a red slider appears, then drag the slider. Then press and hold the Sleep/Wake button until the Apple logo appears. 

https://support.apple.com/en-us/HT201559

force power down if the above give you trouble.

Hold down both the Sleep/Wake button and the Home button. Ten seconds or more.  Hold until the Apple logo appears.

more details on re-booting:

    http://ipad.about.com/od/iPad_Guide/ss/How-To-Reboot-Your-iPad-Power-Off.htm

Restore to factory settings by loading the latest version of ios that your machine will support:

   Do a full backup of your device.  Twice is best -- cloud and computer.

       https://support.apple.com/en-us/HT203977

   "You can use iTunes to restore your iPhone, iPad, or iPod touch to factory settings and the latest version of iOS."

       http://support.apple.com/kb/HT1414?viewlocale=en_US&locale=en_US

   "You can put your iOS device into recovery mode, then restore it using iTunes.:

       http://support.apple.com/en-us/HT201263

You should, always maintain a free storage space amount between  4-6 GBs.

Before just randomly deciding to delete stuff willy nilly, you can either backup everything to iCloud (if necessary pay a monthly fee for higher tier storage amounts other than the free 5 GBs of data storage space) backup to iTunes on a computer or backup to something like a WIfi enabled wirelees, portable hard drive or wireless WiFi USB flash drive.

Another way to gain space is to remove apps you no longer use and thin out any music, movies, videos and look through you photos to see if you can delete any that may not be ones you want to save.

I am going to leave you with a list of things you can, also, try to speed up your iDevices' performance.

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".

Try a 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 any of my above suggested fixes were a fail for some or all of your iDevices.

I have since found that my iPad 2 and 3 have become "like new out of the box" fast performance-wise by doing a variation on a normal erase-reset/restore procedure.

On both my iPad 2 and iPad 3, I did a backup to iTunes, then did and erase-reset restore as new iPad, first. Then, reconnected my iPads to iTunes on my Macs and then, I did a restore from backups.

The performance increase from this were noticeable and apreciable and both iPads are operating with a like new performance speed and, in addition, both iPad models have gotten an appreciable amount of free storage space returned to them.

Here is the procedure for this restore procedure and this has already worked, sucessfully, for one other iPad 2 user so far!

First, connect your iPad to USB and sync and backup your iPad to iTunes (make sure your iTunes is up to date).

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 and ask if you want to set up as new.

Select OK. If iTunes begins to try and sync, again, cancel the sync.

Once your iPad is setup as new and your iPad appears in iTunes, again, CANCEL the sync, once more.

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.

The overall thing this will do is give your iDevices back some needed free data storage space, but this is supposed to return your iDevices back to near previous normal performance and operation.

Good Luck!

Did you try turning on the Reduced Motion setting?

What are the results so far?

ANY of your devices running better?

You have my last reort solution, which is my own variation on the "normal" backup/restore procedures to still try.

What is the status of your devices?