"Let's see...now he is...Prone, I'm Charging, but he was Surprised, which means...no, that's on page 115..."
"Um....ok...so 75% to hit, plus 12% for this round, add in the 37% from the weapon...carry the 6..."
"Wait....what do I roll to hit again? I can't remember".
"OK, let's see I do 4 points of damage--dangit, I can't hear over the store radio--I SAID 4 POINTS, AND THAT'S--HEY GUYS, DO YOU MIND? WE'RE PLAYING HERE!"
"No, that isn't how that At-Will Power works! Yes! Look it up, then!"
Ah, Resolution Lag (RL, for abbreviation purposes). This is a topic I covered on a blog now perhaps forgotten, and I've made some updates to this article, which was one of my top 3 most-visited at my old site.
Now, in gaming, resolution lag refers to anything that slows down the resolution of a conflict. Lags can be mechanical in nature (a complicated system), human-wrought (a player being unfamiliar with a system or poor at math), or even environment-based (a gaming area with a lot of loud distractions). Not exactly a profound theory of academia, just the identification of something that can screw up a game.
The thing about resolution lag is that it's such a simple concept, but it's one that doesn't seem to get talked about that much. And to my mind, it's one thing that can kill any cinematic campaign for sure, and can cripple many others. With resolution lag, players get bored, what should-be high-intensity, high-powered scenes of conflict go by the wayside, and players can feel left out as scenes not involving them drag on and on. Nor are "skill monkeys" or combat-light games exempted from this threat. A social confrontation, battle of wits, or any sort of skill/talent use can suffer from resolution lag as well.
Now, I don't think there's really a way to quantify resolution lag, as it will differ from game to game, person to person. For example, one might assume that Rolemaster would be a high-lag game (due to multiple modifiers and chart-based resolution), but I've been in groups where combat is resolved faster than a comparative d20 encounter. You can point to a game and say that certain mechanics might make them high-risk for resolution lag, but you can't say for certain that they'll have it. Certain groups find the multiple adders/modifiers of D&D slow their resolution. Some don't. And so it goes with every system, every title out there. Exalted, GURPS, Rifts, Fuzion, you name it. Experience with a system, play style, ability, and, of course, personal bias will play a large factor into what folks are comfortable with, and what in particular bogs their games down.
Of course, there are minimalists out there who say that the easy fix to this is to simply have shared-narrative power, wherein people in the gaming group take turns what happen. Others will suggest systems no more complicated than a coin flip. In the first case, you can still suffer from resolution lag: a long-winded storyteller, a person anxious to hog the spotlight, or those loving an anal-retentive level of detail can bog this sort of game down. In the second case, simple resolution systems may not only rob you of a more tactical or structured gaming experience (if you want it), but can also lead to lag themselves through long-winded players or extensive verbal resolution of details (i.e., arguing over what just happened). Rules-heavy, rules-medium, rules-lite--any RPG can have resolution lag, for many different reasons. RL is a big tent. One person's simplicity can be another's unstructured nightmare, and one person's attention to detail can be another's nitpicky snore-fest.
In the end, really, you can look at your system, look at your group, look at yourselves, and look at your environment, and ask yourself, "how bad is our resolution lag? Are players getting bored with how long combat or tasks are taking? Do parts of our game stretch on a lot longer than they should? Is it because the system is more detailed than have a need for, or is that we just haven't learned the system yet? Are too many modifiers giving us a headache? Are their too many distractions from our players or our surroundings?" Ask yourself these questions, and then trim the fat. Streamline, focus, adapt, convert, but find out how much lag is too much for your gaming group. And remember: not all lag is bad. That breathless anticipation while you wait to see if you rolled the natural 20 you needed to keep your party alive is a pretty great part of gaming. But if your group is sitting around, not getting to the juicy story bits, sighing through immeasurably long "simple" encounters, and generally resembling a Friday afternoon line at the Department of Motor Vehicles, you do need to ask yourself, "what's the slowdown here?"
As many of us get older, we often find that we no longer have time to game as much as we did before we grew up and had to deal with all this responsibility business, and that a wasted gaming session is a lot more of a nuisance than it was when it seemed like we had all the time in the world. To this I say, find the lag, find the reason, and control it as best you can. That doesn't mean that all HERO players should convert to Wushu, or that D&D folks should just cut out all tactical elements or modifiers from the game. But look at simplifying where you can (charts, player references, learning how and when to adjudicate rulings to keep the game going, streamlining unneeded system bits, and [gasp] even learning more about the system), cutting where you must (changing to a non-distracting location, muzzling the disruptive, and perhaps even changing systems or system versions, if need be), and above all, keeping the parts you like.