I would find Niley's macro and use that, reset=combat for example should be 'reset=combat/8' for the lavaburst. you want that cast sequence to become available whenever lava burst is up. While you may have a perfect number of commas for when you press the keys, your character might be feared, stunned, incapacitated by some undead dragon, healing the tank or what have you. That will insure that your lava burst is up.

Similarly I would make this a 4 button click macro and time out chain lightning in a similar fashion. While its a very short cooldown, you will be able to see that it is timing perfectly.

On all these I would [harm, nodead] this will make slow turn over mobs not waste button presses. Since those button presses won't actually have cast times associated with them.

I would suspect if you are slow on trash that your not transitioning between mobs right and turnover is slow. At some point you need to switch on the focus unit (tank) to the next trash mob and either let the last mob die from magma death, hammers, ret aura, or chain lightning, etc, most likely one or two of your casters will take its head off with the spells they are already casting and or the next ones during the focustarget lag.

So to be clear, burn down first kill order, just inside the red zone for the mob, switch to next mob and the final spells and effects will clean the first guy off the list and there will be a smooth transition and no problems with a huge 'casters are idle' issue.

You can measure this with 'time idle' in recount. If you have idle time, there is something seriously wrong unless you have a dedicated healer who is just sitting there regening.