It sounds like you’re mostly suffering from the constraints of using a Zenith as your Roon Core (slowness, dropouts, etc.). We wrote up a summary of why Innuos products are unsupported here:
There’s no doubt you’d have a vastly improved experience if you were using a Roon Core that meets our minimum requirements.
If you’re looking to upgrade and want something turnkey, then Nucleus is your best bet. Or you can go the DIY route with ROCK. Both are excellent options!
Do you have another device that you could temporarily use as your Roon Core as a test?