Troubleshooting Homey Early 2019

That is gonna be trial and error I think.
What if you disable as much apps as possible, except Ikea & Hue.
See if the responsetimes get better.
If so, enable other apps one by one, to see where it goes slow.

What are your zigbee channel numbers of Hue bridge, Ikea hub and Homey zigbee?

Go to…More>Settings>General and wait for a while.

In Insights you can view the history also per app.