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What is and how does World of Warcraft's Custom Lag Tolerance setting work?

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Good question. I wasn't aware this feature was added to the game client until now. – Brant Dec 8 '10 at 4:37
up vote 4 down vote accepted

Whenever you want to cast a spell, there's a delay between the time you press the button and the time you actually start casting. That delay is determined by how long it takes for you to talk to the server: you need to tell it you want to cast this spell, and the server has to say "OK, casting starts now". This delay is called latency, or more informally, lag.

You can take advantage of this delay to reduce the time you actually spend between spellcasts: just before you finish casting one spell, you start casting another. If timed correctly, you will finish the first cast and immediately start the second cast, due to the time it takes to talk to the server.

Of course, in order to do that, you need to know exactly how long it took to talk to the server, and since we're generally talking a few hundrer milliseconds, it's not easy to measure on your own.

Custom Lag Tolerance is intended to help you with that: once you know the approximate latency you're playing with, you can set it up and the cast bar display will take this value into account so you can chain spells more effectively.

Instead of using the built-in functionality, there are also addons which actively measure the latency for each spell cast and adjusts the cast bar based on that. If you're using PitBull Unit Frames, it includes a module for this which you can enable. Before I switched unit frames, I used Quartz as a cast bar replacement, which also contains this functionality.

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Thank you... I use Quartz. However quartz doesn't work too well when playing with 800 to 1500ms lag. I get an error sometime with I want to queue actions. However, I played around with this setting. Set it to 400ms and I have received less errors and more queued actions. Thank you for the information. – SgtOJ Dec 8 '10 at 2:40
@Brian: Automatic measurement assumes you have relatively stable lag times, which doesn't seem to be the case for you - in the case of spikes, you will end up attempting to cast the next spell too early, because it took a lot less time to contact the server for the second cast - but the timer doesn't know that. A manually set latency like the built-in avoids that, but at the cost of precision when your latency is stable. – Michael Madsen Dec 8 '10 at 2:51
Also, I'm not entirely sure right now, but I think Quartz could also be set up with a manual latency. It's been a while since I used it, though, so I may be mistaken. – Michael Madsen Dec 8 '10 at 2:52
I should correct my comment. Quart does work well. However, it use to be much more useful before Blizzard nerf the /stopcast macro. I could top the DPS charts while playing with 1300-1700ms pings with that macro when I played in Iraq. But this new feature with Quartz helps a lot now that I play from Afghanistan. BTW, normal ping for me here is about 900ms. Much better than I ever had in Iraq. – SgtOJ Dec 8 '10 at 3:00
... But that is because I use a WoW Tunneling service too -- WTFast. Where before I did not know such a service existed. – SgtOJ Dec 8 '10 at 3:05

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