Can you do less is more/routines? Have a set menu (maybe a two week rotation?) so you don't have to spend mental effort on meal planning or grocery ordering since it's always the same. You can also have your kids help cook which will be easier if it's there's a lot of repetition. Definitely have kids help in the cleanup if you can. Little kids actually like chores, even if they're bad at them, so it's great to try and get the habits in place before they decide everything is boring.
How often do you have to clothes shop? Shouldn't be more than once a season, and just order one of everything you want. Lean large on sizing so you don't have to return anything.
I can't help with cutting down on holiday planning time because that's a major part of my stress relief and I'm all in on it all year round.
