When i got to 99 magic with stun/alch i did a 6-9 minutes break for every 30-36minutes stun/alching, which would bring your xp to 140-150k/hr which is pretty good.
@CzarSometimes the bot will equip rune arrows when alching them, can you add a failsafe when it does that? Take it out of equipped and move it to same position as high alch and continue alching.