I have a 5+ year old computer and settings are all on low. I get no lag what so ever and the game runs pretty smooth 95% of the time. I'd highly recommend turning ALL your settings down a notch and playing. Then turn them back up to high one at a time, and see what makes the most difference with lag (turn off) and your gameplay experience (turn on), and find an acceptable setting. If you don't have a brand new computer, chances are you can't run everything on high 100% of the time. And I assume you updated your drivers already.

L20 here, and only noticed the following things: - Some DPS suck. They don't focus fire, so you have 4 elites beating on the whole group for a long time. - Seems like people don't use damage avoidance sometimes. They have skills (not sure what they are), and stuns to help out with healing. - I usually bubble people right before a fight as we move, then seeth for 2 seconds before the fight to get my force back up. You really don't need to start fighting for a few seconds after the battle starts anyway, so I seem to be able to seeth to refill post-bubbling pretty easily. - If I run low on force, I try to consider why that is happening. Does the group DPS suck? Am I DPSing too much? If the group DPS sucks, I often start out the fight with a little DPS to help eliminate a guy or two, plus with the other tactics above (bubbles then seeth), I can often do better than just healing during the fight. - As noted above, use your stun on gold mobs. A few seconds is a few seconds less dps. Also, pop your interrupt at nearly the END of their cast time to really reduce some damage. Obviously those are newbie tips... so take it with a grain of salt.