You're right, here's what one of my hot loops look like:

    func (cc *ComponentContainer[T]) ForEach(f func(*Component[T])) {
     for _, page := range cc.pool.pages {
      for i := range page {
       if page[i].IsActive() {
        f(&page[i])
       }
      }
     }
    }

Still, the interface approach is a total nightmare from a readability + runtime error perspective so I won't be going back & will just hope for some performance freebies in 1.19 or later :^)