So, I've been thinking about the NPC population in Skyrim being a bit on the low side. Now, any tech savvy person could easily explain why: It's the radiant AI, or more accurately; the pathfinding used by the radiant AI.

Pathfinding is very intensive on the processor. Using the A* method, (which is the method most likely used here) it lays out a grid that check terrain and assigns a value to it based on weather it can be passed, or how much it prohibits/inhibits movement, and that value is added onto a rough guess on how far that gird square is from the destination. This process is repeated many, many, many times. Then, after all that, it picks the shortest route. This is just grossly simplified summary of pathfinding. As you can see, it's tedious and wasteful.

I was thinking, 'how do people pathfind?' and since I was walking down the sidewalk with no one to ask, I thought; 'how do I pathfind?'. By memorization: After following a path so many time, you memorize it, so, why doesn't AI memorize paths they're going to take thousands and thousands of times?

All you need to do, is have an NPC record certain paths it takes regularly, and run a quick check to see if that paths available, and if it's on a segment of a known path to it's destination. Then, we're golden. The downside to this is more used disk space, the upside is vastly more populated worlds or complex AI.

I know, Beth may already have something similar in place. but if not, then why not? This could make TES much more alive!

You do reason and examine sensory data while pathfinding IRL, though. You don't just memorize and repeat a path the way ants follow a pheromone trail.

It's better than Oblivion, at least. Oblivion has even fewer NPCs in cities than Skyrim does. Not that there isn't room for improvement, of course...

You MUST be joking. Oblivion had way more npcs in citys and at the same time. Oblivion also had more complex AI in citys. They even left the city at times.

Not sure of the stats on this - there must be infor to check on this - but I wonder if this seems the case because OB had bigger cities.

so,a question from a complete tech luddite.
how does this game differ in doing pathfindind from a game like assassins creed 2 for example,where there are hundreds of npcs in a city environment and some of them are on horseback?
just curious as ive no idea how this all works! cheers

On the whole Skyrim tends to have slightly fewer buildings than Oblivion, but more NPCs. Here are numbers comparing two towns from each game. The first is number is total number of buildings both inside and outside walls.

Solitude - 23 (83 NPCs)
Whiterun - 26 (78 NPCs)

Chorrol - 25 (55 NPcs)
Cheydinhal - 26 (60 NPCs)

Morrowind has more NPCs than either Oblivion than Skyrim. Here are NPC counts from two Morrowind towns:
Balmora - 94
Ald'ruhn - 90