Default [Q] MultiTasking broken after day of use (or memory leak?)

Hello everybody.
first of all i just want to mention that im really happy with the phone, especially after moving from galaxy s3 with its horrendous memory tasker and RAM.
ive noticed a problem thats been really bothering me:
after a day of use , maybe more, there seems to be a lot less memory available for the device, resulting in chrome/chrome beta reloading every time that i go back to it, even without performing any actions or loading new apps - simply moving to whatsapp for example and back to chrome - Bang! the browser reloads. I want to emphasize that this is not the normal behavior for chrome, as this does not occur after a fresh restart.
When i go to services running, there is about 800mb of ram left, but when i go to ES task manager, there is only 400mb, i dunno the cause for this difference, but i do know that despite disliking task managers very much , Pressing "Kill ALL" will restore the desired behavior for a while (no reloads).

I tried to root the phone and install Greenify , but this doesnt seem to be helping.

did anyone notice any similar behavior? thanks.