[wrxtasy]

So it's not worth to upgrade performance wise, to let's say a s912? Will I see any difference in speed? Some of my add-ons are part time cpu heavy, they do work on my Odroid but would be nice with a little more boost.

I need to buy a new one, planning to use my old odroid c2 in the bedroom. But then I want something better than I have today.

Ultimately CPU intensive Kodi needs Intel iron if you really want snappiness. It's single Core CPU performance is what you want for Python scripted Kodi Addons and Skins, and Intel does that well vs cheap ARM microarchitecture.

The A10X Fusion in the recent Apple TV 4K is the most impressive ARM chipset on the market, it's a bit of a beast !

S912's will be a little bit quicker, but not much at all vs the tweaked C2. Especially if the C2 is already using eMMC flash storage. THIS S912 combo would be cost effective.

Otherwise consider a NVIDIA Shield, that will definately run Kodi v19 M when heading into future Kodi.
Just make sure you can return it if you are one of those unlucky users that has a 4K HDR TV that cannot handle SDR content combined with the colorspace conversion the Shield uses.

Kodi Leia gives ARM devices a bit of a speedup bump as well.