Unfortunately, my luck was short lived. Memory leak is back and it seems like something in the ROM causes it, some setting. I don't know which one but everything was OK yesterday and later I put a lockscreen wallpaper in and some other tweaks through the ROM settings and the same thing happens: it start to leak RAM and goes down, even when all apps are closed with the close all button and I wipe the memory with Clean Master, it is still low (around 300 MB or less even with no apps open and CM used) paired with sluggishness.
So I am reverting back to GPe soon. I don't think it is my apps since the memory was stable yesterday, it seems to be related to something else. I activated Halo and Hover but have a hard time to think that they would cause this.