Gala and Xorg are always above 13%, even if there are no other windows except Terminator. It drains the laptop's battery and keeps the laptop's cooler always on.
I can't remember when I first noticed it, might be a month ago, or a couple of months. But it started bothering me now because of the cooler (probably the warm weather made it worse).
It's 0.4.1 Loki 64 bit, there are no updates available.
Linux blackbox 4.4.0-128-generic #154-Ubuntu SMP Fri May 25 14:15:18 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
PS: It's getting even worse when the screen is off due to inactivity. The screenshot below is made using an ssh session from another computer: