1080p hi10p h264 content on a pi 4 is cpu decoded on a single thread and lagging BADLY.

So it's to be expected that hi10p h264 content would need to be cpu decoded as there isn't anythign that can do hardware accelerated decoding of that profile. The problem is that it's only decoding using a single thread on the cpu when I check with htop. This is causing it to lag really badly, to the point of being unwatchable. Audio and video is de-synchronizing etc. When I load kodi on my desktop (ubuntu 18.04) it is properly multi-threaded. What do I need to do to make hi10p h264 content properly multi-threaded on my pi 4 using libreelec?