Taming and breeding don't care about ingame time passed, only real time passed.

However, they DO care about the area being loaded. If your boar farm is far from your base, Or if you're just not spending much time at your base, they'll tame extremely slowly and waste lots of extra food doing so.

Every piece of food is time based and roughly 33~% tame progress normally. It only progresses taming if the area is loaded- But still counts down the timer no matter what. So if you feed them and then leave on an exploration expedition, most of that timer gets wasted.

So basically, feed your boars and then stay nearby.