Pathfinding causing slowdown?

On the campaign map towards the end of my campaign, it seemed like if I had already ordered a unit to move and it could move no further and I gave it a second order to say a different settlement, the unit would start twitching. The game would also get choppy because it was trying to calculate a path to get there. As soon as I moved another unit the choppiness would go away. If I entered a battle it would go away as well. If I loaded a saved game it would stay slow.

All I have is vanilla RTW with the Bug-fixer. Could bug-fixer be causing this? I never played the game without bug-fixer.

hardly...

Campaign map lag. Well I'd say its caused by a background program, but since you can cancel it by doing certain moves it has to be the game. perhaps you have a corrupted saved game, especially if you are having trouble moving units.