A very small number of us have taken this path. I have 3 hubs. One is for my downstairs ZWave. The second is for Upstairs ZWave (and my giant collection of 5 Zigbee )
A third hub was purchased for the reason you mention... I don't want any of my Hubs-with-Radios to be slowed by an app. Only Hubitat apps run on my Hubs-with-Radios. Amazon, Chromecast, Homebridge, Dashboard and Thermostat Scheduler all run on my third hub: "coordinator."
On a Hubs-with-Radios I will run RM, Lutron, Lock Code, Link to Hub, and Advanced Button Controller.
This has an odd result.. no slowdowns anywhere. You'd expect that 'coordinator' would run slow from at least one of those apps. Not so far.
Caveat: Link to Hub is great BUT it does NOT forward all commands and attributes. My Garage Door Opener (GDO) is a good (bad?) example: On 'coordinator' only Contact is available. I cannot open or close the GDO from 'coordinator' without a workaround (virtual devices).