xorg cause high cpu usage with kernel 4.14

[lichaowuwei]

I use the kernel 4.14 on beaglebone black and ai， both xorg cause high cpu usage. for example, i move the curse on the terminal, the terminal and xorg will cause high cpu usage showed in commant top.
when i use 4.9 or 3.8 kernel in beaglebone balck, it not.
anyone know why? how to fix or config to solve the problem?
thanks

[RobertCNelson]

Well the BeagleBone-AI has a 2D accelerator:

sudo apt-get update
sudo apt-get install xserver-xorg-video-armada-etnaviv

Section "Monitor"
        Identifier      "Builtin Default Monitor"
EndSection
Section "Device"
        Identifier      "Builtin Default fbdev Device 0"
        Driver          "armada"
EndSection
Section "Screen"
        Identifier      "Builtin Default fbdev Screen 0"
        Device          "Builtin Default fbdev Device 0"
        Monitor         "Builtin Default Monitor"
EndSection
Section "ServerLayout"
        Identifier      "Builtin Default Layout"
        Screen          "Builtin Default fbdev Screen 0"
EndSection

Whereas the BeagleBone Black has nothing.. CPU only...

sudo apt update
sudo apt install read-edid xserver-xorg-video-fbdev

Section "Monitor"
        Identifier      "Builtin Default Monitor"
EndSection
Section "Device"
        Identifier      "Builtin Default fbdev Device 0"
        Driver          "fbdev"
EndSection
Section "Screen"
        Identifier      "Builtin Default fbdev Screen 0"
        Device          "Builtin Default fbdev Device 0"
        Monitor         "Builtin Default Monitor"
EndSection
Section "ServerLayout"
        Identifier      "Builtin Default Layout"
        Screen          "Builtin Default fbdev Screen 0"
EndSection

Regards,