Need some WHM Speedrunning tips please

[DreamWeaver]

Personally I prefer to Swiftcast my first holy as I want the 1st stun to go off ASAP, if I were to hardcast Holy, it'll take an extra 3 second before the mobs are stunned.
Another minor advantage is some WHMs mayb experience if you hardcast 2 Holys in a row without waiting, the 2nd Holy's stun will have no effect, thus if you SC your first Holy, your second holy's stun will take effect due to you having to wait for the 2.5 GCD after the 1st Holy.
Last Advantage (for serious min-maxers only), you're able to use your PoM oGCD buff during the 2.5 GCD down time, thus ensuring 0 time loss +full PoM duration for the Holy Spam.

Find whatever works for you, as long as everything melts and the tank is still standing (bonus points if he wet his pants a little), it's all good

[Saseal]

Find whatever works for you, as long as everything melts and the tank is still standing (bonus points if he wet his pants a little), it's all good

xD I love that last part

[Sunako]

I usually wait untill all mobs are at the stack -> divine seal -> cure2 until tank is 100%->regen -> one more cure2 -> cleric stance -> swiftcast -> holy -> POM -> keep spamming holy - >if mobs are not dead and tank around 30% use benediction and keep spamming holy - > if tank is 40-50%(and no bene) take cleric stance of and use cure2 until tank is top. I m using shroud almost every time it is up and sometimes for aggroes. Sometimes u need use less holy for generating mana. Full piety gear help bit with that.

[TheodoreMcIntyre]

I Stoneskin and Protect before they run off and then hold off until they have aggro on everything and have finished the pull, then I just sorta Cure II over and over and over, depending on how geared the tank is and how hard the mobs are. If you want speedrunning practice, try WP speedruns. That was where I learned the basics of speedrunning stuff. Or, even Brayflox Hard would be a good choice.

[Sirtimid]

Everyone has mentioned the basics in an excellent manner. I'll just say that with Holy Spam it's very important to stagger your second cast a bit. That way you will get a total of 7 seconds of stun which is absolutely fantastic as a) it will allow regen to tick and top up the tank b) flares should be going out at the time and c) mobs will be dead or nearly dead by then.