Try these tricks (providing they are applicable!):
Lower down the number of enemies under your control, but make them stronger. This way, you won’t have to deal with so many pawns.
Don’t force your NPCs to fight to death. Assume that once, say 25% of your pawns are wiped out, their leader halts the fight and asks to parlay, or that if 75% of them/their leader go to the ground, the rest escapes.
Tucker’s Kobolds.
If a combat action leads to multiple dice rolls one after another, roll all of the dice at once - this speeds up the game.
Use combat managers/helpers - Excel file, dedicated software, whatever helps you in math, use it.
If the combat becomes too overwhelming, introduce some unsuspected elements. Sudden earthquake, volcano eruption, castle falling down, incoming of a truly powerful enemy, etc. Have some good in-game explanation for such an event!