HA responding very slow

Everything was working just fine. HA on intel, zigbee response was under a second.
For no apparent reason it suddenly went slow; 10 seconds or so delay.
Logs show nothing interesting. What is interesting is if I toggle a light off for example it can be 10 seconds before it shows in the log. So I’m guessing not a zigbee issue?
Upgraded to the latest core, rebooted etc. still the same.
Any ideas where I should be looking to find the issue?

Think I can answer my own post here.
A light switch has started to act strange and I assume therefore can flood/corrupt the zigged network?. I physically removed it and POW! - responsive speed of the entire network back!!!
My question now is : Is there any way to check/find rouge devices? - I was lucky I think…