D&D does throw around a lot of numbers at high levels. Other systems that don't go into "high levels" don't throw around those bigger numbers, and so are quicker, easier to calculate, etc.
In fact, I think part of the reason we can have convos about how high-level D&D involves a lot of math is purely because they *finally* got High-Level D&D into a form that is playable without resulting to DM caprice....it's the first success, and it does involve a lot of math.
What is "a lot of math" varies from person to person, of course. It definately involves more than low-level D&D. For my milage, it's not too much. I can add +x pretty quick, no problem. If you can memorize times-tables, you can add numbers 1-10 without much of a problem.
You do encounter more varied scenarios, and there are more options, and this does bog down play. The way I've helped it IMCs is by encouraging specialization. If he's a Paladin, then I know he's good against Chaotic and Evil things, and otherwise won't have as many options. If he's a fire-wizard, I know he'll have a lot of bonuses against water elementals, not so many against demons. This helps limit the types of things they can do, and makes the occasions for adding up a lot of dice specific to the moment that the character shines at.
There hasn't been much of a problem IMCs adding up the bonuses and deciding on a course of action before taking the turn and resolving it quickly. No more than introducing new people to the game, anyway. And the more you play high levels, the more familiar the bonuses and strategies become.
So instead of bemoaning the options, play it, re-play it, and play it agian until you're comfortable with it. Or just ignore it.
