How do you get out of stalemates?

Hey, I've been a long time casual AoM player and usually only played the campaign maps, on easy difficulty. I've just recently got into playing it again, but decided to improve my gameplay skills. I've been playing against hard AI since I'm not confident enough to try online yet, but it seems to me that if I don't wipe out the AI during classic-heroic age it becomes immensely time consuming to do so after I hit Mythic. Battles just drag on and on forever as resources cease to be a problem and both sides can produce units faster than they are killed. Even Titans don't always turn the tide, 20 pop is a huge debuff for me when maxed out on villagers and a decent size caravan route, so yeah. It becomes even worse on water maps. Eventually I can micro my way into their base, but it takes way longer than I think it should. What do I do in those situations?