I have an old YouTube app on my iPad, and it still works fine. One of the more responsive apps on the device. I get nagged nearly every time I use it to update to the newest YouTube release, but that's impossible. I'd first have to upgrade my OS, and Apple no longer releases new OSes for this generation of iPads. So, I'm stuck with an old YouTube, which mostly works fine, and an occasional nag message.

I'm sure within a year or two mine will be like yours and YouTube will simply no longer work. But, for now it's in a relatively good spot where I can use a version of YouTube designed for this particular hardware that doesn't feel sluggish.