Ipad very slow with ios15.1

Having updated to iPadOS 15.x, you cannot restore iPadOS 14.8.

If your iPad is misbehaving, a forced restart may be helpful - as this will often resolve an isolated software or performance problem:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

Have you tried connecting to a different WiFi network - preferably a 5GHz network. WiFi performance on congested 2.4GHz WiFi networks is not uncommon.

Recommended settings for Wi-Fi routers and access points - Apple Support

I’m unable to replicate your performance issues - and see expected throughout for both 2.4GHz and 5GHz WiFi networks.

A further step to try is to reset your Network settings:

Settings > General > Transfer or Reset iPad > Reset > Reset Network Settings

If you continue to experience difficulties, you would be well advised to seek assistance directly from Apple Support. The Get Support link can be found at top-right of this page.

Alternatively you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

hello ipad_dmk

look like your having a ipad problem

you may try to force restart hold the power button and power button

it may be your ipad storage is low or the ipad can't support ios 15.1 well