So, today a senior engineer from tp-link reached out to me and informed me that it is normal to get CPU usage spikes when you set one deco as the main router and have other deco units connected to it. Also, he informed me that if I use another router as the main router and setup the deco's as AP's it will reduce the CPU usage spikes on the main deco (which is something I have tried but I was still getting CPU usage spikes to 100%).

It seems to me like it is a hardware limitation even though I believe the unit have a 750MHz dual core processor !!!

@meyouthis hi use my deco m4 unites as ap and I do have the spikes too and they are using 100% of cpu and network simply freezes is impossible to use!

@marine_tugah hi there Marine, for me the network does not freeze when I set my deco m4 units as AP's but there is sometimes a slight delay when I browse the internet (some webpages take longer time to load) and it's still happening with the latest firmware update 1.5.0 .. you may try updating your deco's to the latest firmware and I hope it solves your issue. 

@Choklate A HA, found why the wife keeps telling me her web calls people cant hear her and its freezing, Tried multiple things, moving them, reboots you name it. Then today found the hidden admin page which shows CPU load HIDDEN unlike the app which HIDES IT.

Reason can only be because its known to be sub optimal to make it cheap.

Now I know why it doesn't work properly, because Deco is cheap crap. 

Can the admin please inform us how we get a refund on these devices which have a major design flaw and do are not fit for purpose so under the consumer act in the UK, even without a warranty are liable for refunds?