RPI 2 running at 100% CPU how to find the bottleneck

So I have a problem that my lights turn on several seconds after i press a button either in browser,tablet or physical switch, sometimes it does not even execute the rules. This is due to the fact that the RPI2 is running more or less constantly on 100% CPU

So what I have done now is to get a RPI3 which is supposed to be 30% faster, I installed a clean openhabian image on it, set up the expert configuration http://docs.openhab.org/tutorials/beginner/1sttimesetup.html, because I will use some 1.9 bindings

So my question is how cpu consuming are those UI on the RPI? Should i disable them? How to do this?

My idea is to install 1 and 1 binding to find out where the bottleneck is, so in this order

DMX OLA(with ola running in background) 80 items
GPIO 30 items
Persitance (all items, once a day and on change, is that bad strategy?)
OpenhabCloud(all items)
HueEmulator(30 phrases)
Netatmo(1.9)(130 items)
http(with json transform)(8 itmes)
exec(python for miflora)(30 items)

Is my setup especially heavy or is there one binding in OH2 that just eats cpu?

It’s unlikely that OH is truely eating that much CPU. I have yet to encounter an OH installation large enough to have this kind of problem to saturate a RPi2.
You are probably hitting a selfmade script programming problem, for example an ever-repeated rule to crash each time, or a rules file that get changed and recompiled again and again.

I’d ramp up debugging to find out, specifically

or the equivalent in OH2

If that doesn’t give a clue, yes then you can start removing bindings, or items, or rules, until you spot significant improvement in CPU usage, then investigate those items and rules that you had just removed more closely to find out why they eat CPU.