Skyrim modders create custom content for the game.
Skyrim modders create custom content for the game.
You could manage that scenario by limiting script usage to just a few NPCs, keeping the total under 30 while still achieving your goal.
Start with a simple small village, as the battle for Whiterun should involve only around 40 NPCs.
The town should have around 100 or 200 NPCs, but running more than that at once might slow things down. A smaller group of 30–40 seems more manageable.
If you have the same quantity of NPCs as in Skyrim, adjusting their AI to make them feel more authentic would help improve realism.