Hey @ChuckPa, Sorry I can’t believe I totally forgot to add it lol. Synology DS918+, running natively off the package (not docker)
I think I was able to answer my own “why” question thanks to @trumpy81’s comments guiding me in the right direction. Looks to be the single-core limit of HW acceleration as discussed in another thread where burning subs is just too much for a single CPU core to handle and it kills performance.
I’d appreciate any further insight / confirmation though 
