We also have the same building set up with a TON of other ioT platforms and gear for testing and have literally no problem with other apps connecting at speed.
For example we have a complete Alarm.com monitored system , a complete Vivint monitored system, Hubitat Hub/Platform, Smarthings Platform , Googles Suite of products, 40+ Hue light bulbs, etc, etc.
All of which have apps that connect multiple services together that only take within 1-2 seconds tops to connect via mobile.
I am puzzled at how C4 is featured as a premier platform, and IMO has the BEST looking UI of them all, Takes 10x longer to load, and Cost 10x as much at the same time.
Figured someone on here would know something if its been going on for a while or just an overseen error on our part.