Supposedly due to the presence of latency, there are small periods of time that occur in between spell casts around the order of 50-200 milliseconds. These gaps apparently happen even if you are furiously spamming your hotkeys as fast as you can. Obviously gaps in casting of this magnitude can seriously decrease long-term DPS. I decided to test it out for myself tonight using a timer mod I have (Flextimer). I made a macro for my Fireballs that read...

The second line merely creates a countdown timer that lasts 9 seconds. What I would do is hit this macro and then continously spam my Fireball key until the timer was done. Theoretically, the third Fireball should have finished casting just as the countdown timer finished. What I was seeing, however, was that my third Fireball still had half a second or so left on it when the countdown finished, sometimes more. I suppose this lag issue has been known for a while and isn't anything new, but what methods (if any) are people using to get compensate for this problem?

I've seen some people using macros with /script SpellStopCasting() in front of /cast Spellname(Rank #) and just hitting it when the current cast is close to finishing. This seems to work well, but there's always the chance of timing it incorrectly and cancelling the inital cast before it's finished which of course would slow your DPS down just as much as any amount of lag.

Other than that, I haven't really heard of any work-arounds, but it seriously annoys the hell out of me every time I'm casting spells that they could be going faster. Anyone know of some other methods to improve upon this, maybe a mod or another macro?

I am watching this thread with interest and the hope that mages or warlocks will post some relatively hard numbers on actual improvements vs their latency.

Nice mod -- exactly what I was looking for.

Tenarius, I'll run some tests tomorrow with and without the mod to compare numbers. It's hard to do outside of a raid setting, because I need a target that (a) won't attack me and interrupt spells, and (b) will live long enough to sustain quite a few consecutive casts.

I remember seeing some numbers posted by Cirk (wrote fastcast) that implied that he was seeing losses (from theoretical maximum) of ~10% of the theoretical number of casts with 200-300ms latency, and was recovering a significant amount (5+%) of those casts via Fastcast.

Having played with it a bit on my mage alt, if you set the latency protection properly, it does seem to speed up next cast.

Sometimes it interrupts casting too early.

I used to play with 350-450 ms latency. Some of my Australian and Europian friends have latency exceeding 300ms as well. I've used the mod ever since it came out and I've noticed a significant improvement in the actual casting time. The difference is most noticeable on fights like Vaelastrasz or Princess Huhuran phase II.

The only problem I've had with it is that sometimes it cancels heals inexplicably. It doesn't happen often enough to discard the mod completely but it really hurts when you are furiously mashing a button to get a heal in but it gets cancelled near the end of the cast time.

Using spellstopcasting is a major improvement in dps when you have any lag beyond 200ms. Even at 200ms, you can still squeeze our an extra couple of %.

Personally, I prefer to do it with a manual spellstopcasting macro as that lets me adjust when I "stop the spell early" on the fly, which is very handy in spiky lag, and I also don't always want to use the trick.

But either way, I can't imagine a dps caster in a current raiding guild not using this - it's that big in terms of dps. You spend talent points to get a couple % increase dps, do you not? This increase is FREE by being a little less lazy and using a macro or installing this mod.

Can't underscore enough how awesome this is, I would seriously consider a dps caster who doesn't use this to be playing improperly.

The problem with the reprted latency is that it's an average. So if one in 5 times a packet takes 500 ms and the other 4 times it takes 100ms, you get a reported 200ms latency (well, sort of). The result being that mods like Fastcast and even good ol' hand-eye coordination on a "SpellStopcasting(); cast x" macro will prematurely interrupt your spell.

When it works, though, fastcast makes an enormous difference, particularly if you use Scorch.

I generally use it at 300 ms padding for healing, as interruptions are much more of a problem with healing than with damage, and if my ping is fluctuating enough to still get cancelled spells, I'm pretty much useless anyways.

On my mage, 50 ms padding made rank 1 scorch go from ~30 dps to ~37 dps -- about a 20% increase.