Suspend KWin X11 compositing when certain windows are in focus and fullscreen. Looks in ~/.config/suspend-kwin/app_list for programs to suspend.

suspend-kwin.sh

#!/usr/bin/env bash

# Suspend KWin X11 compositing when certain windows are in focus and fullscreen

# Requirements:
# qdbus: suspend compositing, check status of compositing
# xprop: find window in focus and if fullscreen
# The "Suspend Compositing" global shortcut to be present and enabled

# Credits to: https://askubuntu.com/a/1017567, https://bbs.archlinux.org/viewtopic.php?pid=994356#p994356

# Specifiy apps to suspend via their window class name
# Run this command to list the class names of windows as they are focused:
# xprop -spy -root _NET_ACTIVE_WINDOW | grep --line-buffered -o '0[xX][a-zA-Z0-9]\{7\}' | while read -r id; do xprop -id $id WM_CLASS; done

# $class_name is passed to grep
# match a pattern of class names in a file and ignore case
class_name="-i -f $HOME/.config/suspend-kwin/app_list"
#class_name="$1"
#class_name="overwatch"

# Only suspend when app is fullscreen as well
fullscreen_only=true

toggleCompositing() {
    qdbus org.kde.kglobalaccel /component/kwin invokeShortcut "Suspend Compositing"
}

isCompositingActive() {
    qdbus org.kde.KWin /Compositor active
}

turnEffectsOn() {
    if [ "$(isCompositingActive)" == "false" ]; then
        echo -e "    Compositing OFF - turning ON\n"
        toggleCompositing
    fi
}

turnEffectsOff() {
    if [ "$(isCompositingActive)" == "true" ]; then
        echo -e "    Compositing ON - turning OFF\n"
        toggleCompositing
    fi
}

checkKwin() {
    if ! pgrep kwin_x11 &>/dev/null; then
        echo "ERROR: kwin_x11 not running"
        exit 1
    fi
}

red=$(tput setaf 1)
green=$(tput setaf 2)
reset=$(tput sgr0)

echo -e "\nclass_name: $class_name"
echo -e "fullscreen_only: $fullscreen_only\n"

xprop -spy -root _NET_ACTIVE_WINDOW | grep --line-buffered -o '0[xX][a-zA-Z0-9]\{7\}' |
while read -r id; do
    checkKwin
    class_old="$class"
    class="$(xprop -id "$id" WM_CLASS)"
    [ "$class" == "$class_old" ] && continue

    class_wanted="$(echo "$class" | grep $class_name)"

    if [ -n "$class_wanted" ]; then
        if [ "$fullscreen_only" == "true" ]; then
            is_fullscreen="$(xprop -id "$id" | grep "_NET_WM_STATE_FULLSCREEN")"

            [ -n "$is_fullscreen" ] && \
            echo -e "${red}$class_wanted${reset} - in focus and fullscreen - should be OFF" && \
            turnEffectsOff

            [ -z "$is_fullscreen" ] && \
            echo -e "${green}$class_wanted${reset} - in focus but not fullscreen - should be ON" && \
            turnEffectsOn
        else
            echo -e "${red}$class_wanted${reset} - in focus - should be OFF"
            turnEffectsOff
        fi
    else
        echo "${green}$class${reset} - in focus - should be ON"
        turnEffectsOn
    fi
done

Example .config/suspend-kwin/app_list:

overwatch
witcher3
bf1
bf4
gta5
batmanak
csgo_linux64