Midori is not required if display output on RPi is not needed.
Menu > Settings > Disable local browser : saves around 6% CPU load and 45MB memory.

Upgrade from default Midori to latest version without errors:
Problem: Too high CPU load, 250+%, while playing. ( RuneUI Enhancement can fix only while stop )

• pacman -S midori upgrade alone breaks Midori
• Fix dependency errors

/.config/midori/config

...
# must match local screen
last-window-width=1920
last-window-height=1080
...

(stylesheet and extension should be removed)

/.xinitrc

#!/bin/bash

exec midori -e Fullscreen

restart

# stop x
killall Xorg

# clear cache
rm /root/.config/midori/history.db-shm

# start x and midori
xinit &> /dev/null &

(manual refresh may needed)

note

• /root/.config/midori will be created by xinit midori
• then create .xinitrc