Yes. I bet you there's one of those 'red squares' from Sorcerer King in there. Solved in SK, but it's a mysterious error or something that shows up in a map as a red square. Kills performance.

If one were to open the map in the editor, the red squares would show themselves.

These battles are indeed a chore to go through, especially if one ambitions to clear the swampy Wildland in its entirety. This new tactical map used for the Asag skirmishes (with an East/West configuration) has the exact same problems as the older swamp map (with a North/South configuration) which has been around since the FE days. I'm pretty sure the greatly reduced battle speed comes from the animated vegetation hogging far more resources than intended. Who needs dancing trees anyways?

There is another considerable problem with this new Asag map. Due to the cramped design, sometimes Morian will not appear to fight battles because there's not enough available space to welcome his bloated mass, leaving only his minions to be fought. A far too easy win for such a hefty prize.