We have an AoW campaign hitting levels 15-16 now. In recent levels, we've seen combats slow down, not during the actual fighting, but in the prep time. Basically, we almost never get caught in a fight that we do not know is coming, so we are always prepped before the swords come out. Since we are in a party of 4 clerics, there is a **LOT** of buffing that goes on before a fight. I think in the last couple of fights, I've had something like 25 different spells active on my character, each one offering different bonuses or abilities, some of which stacked and some of which did not. The combat itself might liast 6 rounds, which is maybe an hour of game time, but the prep work takes at least an hour by itself, and that is for some very prepared gamers.
The world itself is less of a hindrance at these levels. Our characters are routinely immune to a variety of effects at any given time, and can muster up immunity to any particular effect with a little advance warning. From a cold arctic mountaintop to a lava pool, with a little advance notice, our characters can wade right in.
Distance itself also stops being an issue. We don't camp anymore. Our characters can wind-walk or teleport so often and so far that we are home for supper every night, even if we are off on another plane. Supplies and shops are effectively right next door all the time, because a quick teleport to the big city magic shop can net us whatever specific antidote we need to the problem at hand. Effectively, our little home town just turned into the Hall of Justice, where we reside between adventures.
Money is a big issue. Not the search for money, but trying to explain the disparity. Our PC's might toss out an old magic weapon when a better one comes along, and that old magic weapon is worth more than the entire town where they live. Assuming they just want mundane goods, they can buy up every shop in town, plus the houses, livestock, land, etc. But they are still expected to submit to the will of the aristocracy, if one is present.
The remedy for all of this IMO is not to try to fight it, but to instead revel in it. Really push the Hall of Justice / Leage of Superheroes concept. Those daily scry checks let the mage watch for upcoming adventures, and the heroes gear up and teleport out to take care of them as they occur. In the meantime, the characters hob-knob with the rich and famous, jet around to exotic locations on a whim, and generally lead the life of superheroic characters from myth, because that it what they have become. In between, they deal with politics and sponsor lower-level parties to handle lower-level threats.
Something else that I've noted is that the game world doesn't really match up with how quickly the PC's gain their power. Basically, the RAW will let your PC reach level 20 in a couple of months game time if you can keep finding appropriate challenges. Even for a fighter, that seems discongruous to go from a kid with his first sword to the best warrior on the planet in 2 months. For a spellcaster it is even more so.
One remedy I would suggest, and this is something I used in my d20 Modern campaign for similar reasons: Run the adventure in episodic format. Have a clear beginning and end to each adventure. Insert a "Gap Between Adventures" rule to slow down the game time between adventures. The gap runs a variable amount of time, but at least one month per average level of the party.
So now, the 10th level party just defeated the white dragon that was plaguing the north villages. They go into town to shop and rest and figure out their next move. The town has a party and generally goes into epilogue and rolling the closing credits.
Now, about an hour passes at the table, but ten months pass in game time before the next adventure starts.
The next adventure gets ready to start: What have the PC's been up to in that time? Maybe they have been buying land and getting on the good side of some of the nobles. Maybe they have started a school and attracted their first class of students. Maybe they got married and had a kid. Maybe they have even had other off-screen adventures to which they will make reference later. The main point is that when we return to these heroes, they are a little older, they have more contacts, they have a wider reputation, they have closer to the eventual mythical creature that they might one day become.
If you start that at first level, assuming you have just 1 adventure per level, you would pass 3 years of game time by 9th level, even if the "active adventuring" of the party was only for a couple of weeks during that time. You would use up at least seven and a half years by 14th level in those gaps, and eventually fifteen years by level 20, which is plenty of time for a young lad from a small village to become a seasoned mythical warrior known throughout the land.