Playing single player on a huge map. PC specs:

3.2 GHz Pentium 4, single core
2GB RAM
GeForce 7800 GS (distributor overclocked)

The game is pausing for a split second maybe 1.5 or 2 seconds. It's not an FPS issue, as the pausing happens even when zoomed out. Almost like the load of having a huge map with 9 enemies is too much, and it can't finish all it's processes before the next cycle, so it hiccups. It is regular, though, not condition-dependent; you could set your watch to how regular the pauses are.