Extremely slow ios 8 on my ipad mini - downgrade how?

I have ipad mini I think it's first generation - Model A 1432, MD532LL/A

Ever since I upgraded to ios 8.4.1, it's been extremely slow. It takes at least 30 seconds to load facebook, internet page etc.

All apps seem to run very slow.

Is there a way to get this back to originally manufactured version? (like back to whatever ios I had initially when I bought it?)

It's just so frustrating that my ipad mini doesn't get the job done fast enough.

Is there a way to either downgrade my ios version OR have apple change it back to original manufacture version?

I