These often run smoother on limited hardware because they don't require Google Play Services.
If you do not want to install any APKs, you can simply use a modern browser. The mobile web version of YouTube is surprisingly capable. Youtube For Android 5.1.1
If the official YouTube app becomes unusable, try these third-party clients (lighter and still maintained for older Android): These often run smoother on limited hardware because
A lightweight, open-source client that doesn't require Google Play Services. It supports background play and downloads, and it is known to work on older hardware. If the official YouTube app becomes unusable, try
You can copy and paste the section that fits your needs.
The last compatible version is YouTube 17.09.37 (specifically the nodpi or 320dpi variant).
. While the original YouTube app has officially discontinued support for this version, you can still access YouTube features through specific workarounds. Key Accessible Features for Android 5.1.1