Oh dear I feel your pain. I have 4 yo B/G twins. My DS is particularly energetic.
He does seem calmer at 4 than he was at 3 so I'm assuming there qas some kind of developmental thing going on as I remember it well.
My method was to schedule them within an inch of their lives. I always have a plan of the week, taking into account the weather forecast. Nursery, extra cirricular activities, playdates, park trips, museum visits, swimming, looong country walks, visits to castles, baking, story time at the library, crafts, art galleries, scooting/cycling/walking to the shops, dancing in the kitchen etc etc.
We also have quite a lot of play equipment in the garden.
I know that we were out and about more than most of my friends but I really found it helped to keep them busy.
To give you hope, we've really noticed they don't fight as much this year as the last two.