I suggest getting a better router maybe, one that would run all those things smoothly. Otherwise, try connecting your pc directly from the internet cable..
Using magic is a good way to kill them fast, and some magic xp aswell. And the chest always pays back the runes you use (Slayer dart). If you don't want to mage, whip and defender is the best choice in my opinion, whit torso and barrwo gloves.