It seems to me that combat against similarly equipped opponents of roughly even skill will tend to be a slow, cautious affair. Recalling what I can of military history, I seem to recall in civil war type situations there were an awful lot of long, hard fought battles, where in the end a small edge made the difference (better generalship, better starting condition, whatever).
I think in other situations, the rules will make for quicker battles. i.e. if the opponents are less skilled they should be easily bested. If the opponents are less skilled, but have more APs due to followers or whatever, the opponents best chance is still to bet quite large and to hope to get lucky, which even with the characters being cautios should make for a fairly quick fight (and note: this makes sense, think of the shield wall trying not to be overwelmed by the horde of trollkin). If the opponents have better skills, your players will realize that they had best either flee, or get lucky (possibly with the aid of a hero point).
So, one solution is to avoid close matched combats :-/
Given that sometimes the story will demand them, make the routine go faster. For instance, say the player characters have made the effort to get a slight extra edge, and realize that their best chance of winning is to grind out a long slow combat and let their lightning enhanced swords (or whatever) make the difference. Then ask them to set their tactics, let you know if they change them, do the same mentally for the NPCs, and set down to some rapid die rolling without all the effort to describe every interchange dramatically.
For example: The first interchange has happened, with the players bidding 3AP and their opponents 6AP. "OK, as you know these battles can take a while. Until someone wants to change their tactics, let's just quickly roll and do the math." A few minutes later, one of the opponents is down to just a few AP, and you say "In desperation, the short one tries to tackle Hiord and carry him to the ground" This involves a moment of drama, and depending on the outcome possible shifting in tactics on one or both sides, then if things look like they are going to get repetitive again, you can go back to rapid dice rolling.
In summary, go into detail on the dramatic parts, but for the long gruelling parts, just roll and get it over with until things get dramatic again. Obviously not ideal, but it should speed things up and reduce the mental exhaustion somewhat.
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