I've noticed that dogs seem to move at a snails pace when attacking mobs. I thought the issue may have been because I was trying to mess around with creating dogs with custom stats (speed stat, mostly), but I was working on spawning in some regular wolves and "training" them to test how well they attack other mobs, and the issue happened again.

Specifically in this case, I started with a tamed wolf (dog) and put it in an area with skeletons, and it went after them like it was supposed to. I put it into a sit, spawned in an untamed wolf, and let it loose on an area full of skeletons as well. Both times they worked perfectly, but as soon as I tamed the other wolf and set them loose at the same time, suddenly they both were moving super slow, almost like they were just stalking the skeletons and not actually chasing/attacking them. I'm not sure how this issue arose or if others are dealing with a similar problem, but it's definitely kind of annoying especially since I like having a pack of guard dogs with me when I'm adventuring.