Ok, I'll try to explain what I meant a bit more extensively:
"it takes much, much less time to design a good adventure for a party that has very few options then for a party with hundreds of options."
This is my experience, from playing over a decade 3.0/3.5, with loads of different gaming groups, high optimization and low optimization, newbees and experienced optimizers. I don't think anybody can 'disagree' that I have these experiences, unless somebody from mentioned gaming groups who wants to argue I have incorrect recollections of the past. Of course, other people can have other experiences, which are equally valid and should be respected as such imho. If nijineko can build an adventure for a highly optimized party in as little time as for a low optimized party: respect. You need to have a lot more knowlegde of the rules memorized then I have, and probably quite some skills with improvisation. High optimization means often spells & powers, and there are awefully many of those, annd they interact with each other in loads of ways, and give much more options.
Anecdote why I think it's hard: when I DM, I like to create an elaborate setting, with stuff happening at several places in the world at the same time, and several sub plots running at the same time. Which isn't too hard to manage for a party with 5 fighters, and where traveling from A to B takes weeks in game time (plenty of time to interrupt a session with some random encounters and then thougroughly prepare for where they are heading). Now add a wizard with teleport: suddenly, I need to have all my subplots ready, just in case the party suddenly decides to go adventure somewhere else. That takes much more time for me. (This is only one simple example that crosses my mind now, plz don't make too much of it). (I'm not saying teleport is high op, just to be clear, just want to stress the point that higher op leads to more options and more need for preparedness from the DM).
But besides my experiences, it's also a common sense thing for me that in general it is more difficult to build encounters. Imagine a basic dungeon, with corridors, ledges, cliffs, and the occasional underground river. If I have a party with very little options (only normal movement), it's easy to prepare: I know how they are going in the dungeon, and to a large extend how they wil move through the dungeon. But if I have a party that can burrow, swim and fly (and for good measure, become incorporal and ethereal) as well, it's much more difficult. Suddenly, I have to make up what's actually in the river, where it comes from and where it goes to. The party can skip whole levels, find every secret room just by putting their head through a wall. In the first example, I only need to design the dungeon so far as a party can reasonably get in one session, in the second place, the entire thing has to be drawn out and populated.
Optimization, as far as I'm concerned, leads to two things: more versatility and more raw power. Versatility offers much more options, which leads to more things you have to anticipate on as a DM. Raw power (at the end: huge damage, impossible DC's) leads to shorter encounters, again, in my experience, as I said in my earlier post: "removing the rocket tag (save or dies, save or sucks, ubercharging, which is a way of making the game more low-op) leads to longer fights (duh), which sometimes gives a more epic feel." An uber charger is a heavily optimized fighter, a wizard that can cast a DC 35 SoD at level 10 is heavily optimized; lower optimized characters (the same fighter without shock trooper/pounce but with dungeon crasher, the same wizard without SoD's but with blast spells, or a much less optimized DC) lead to longer combats. Again, it is my experience, but to me it is 'common sense' as well.
Of course, you can have longer combats as well: higher op means that you have defenses against the 2000 damage dealing barbarian (miss chances, impossible AC's, immediate action reactions, etc.) or against de DC35 SoD. But that becomes a kind of tactical game, for which you need to know the rules really well, both the players and the DM. That would bring me back to my first point: that takes time/effort.
To make all this rather relative: it's also a matter of choices that a group make; the same amount of optimization that creates an ubercharger or hood can create a stand still / trip build, that prolongues fights rather then abruptly ends them.
Concluding: yes, I do think it takes more time, in general, to build encounters as a DM for high op games, if only because you need to know more rules (spells / powers) and have knowledge on how they interact with everything else. And because the party has much more options that a DM needs to anticipate on. That doesn't mean that there are no people that played a lot of those games, who can make an adventure for a high op party on the fly. I also think that in general lower op games have less rocket tag. That doesn't mean that it's impossible to design encounters that last long even when playing rocket tag, or that every optimized build leads to a game of rocket tag. But using / designing good high op tactics costs even more time to design (for me in any case), and needs an entire group that is quite willing to go 'deep' into the rules.
PS @concerned ninja citizen: hell, I wish I was, instead of at home behind my computer typing this huge wall of text 
excellent points. and so very well stated!
(clarity in writing does not seem to be a strength of mine lately. with which flaw i seem to be annoying certain peoples. =P sorry, if that is the case.)
my comments were, in fact, aimed at the general concept rather than at the specific and absolutely real and valid experiences of waazraath. in my personal experience, it can take as much as 30-60 minutes to completely prep for a high level group, etc, etc.. i should also have mentioned that on occasion it does take me longer, but that is my average. i have also been playing d&d and other rpg systems for over 25 years, which may have something to do with why my experiences have been the way they are recently.
i think it is also a valid point that there is
usually less opportunity for rocket tag at lower levels, though even there it can exist. and there certainly is a tendency towards it at higher levels. again, my comments were intended to be aimed at the general concept, rather than the specific experiences of waazraath. over the years, i have evolved methods and tactics whereby i can let the players have seriously powerful-everyone-braces-for-rocket-tag stuff, and still pull off encounters and adventures without it actually turning into rocket-tag. which i attempted to give a couple of examples of, but were likely also poorly written.
i would very much enjoy sitting and discussing worldbuilding with waazraath, a topic which is of deep and abiding interest to me. i would have to opt for a juicebar, as i have never had alcohol in my life.
despite my poor showing in phrasing my comments to be easily understood as to what i actually meant (at least, in writing - i tend to be better at public speaking than writing), everyone who has actually gamed with me in person comes back to me for advice on plot twists, tricks, possible resolutions to oddball situations that the players/dm has gotten into, and backstory brainstorming for individuals, groups, organizations, cultures, nations, and on up. i have been successfully giving useful dm advice and brainstorming sessions for around 15 years now. several of my dms come to me for help with their other groups which i am not a part of on a regular basis.
it seems that i just suck at writing. *^¬^*
