Slow pacing is pretty much every single game required to go into dampening by default.
But it’s also more complex for me to just completely summarize in this way, because pacing can actually be very quick yet you can still have a dampening match. An example of fast pacing yet still a dampening game would be from the summer finals at the end of legion. Super Frogs went up against XRB to the moon. The best game was on Tol’Viron, and went onto dampening. The games had two defensive oriented teams, yet they both had the potential to kill one anotber at any moment. The games went into dampening, but only because of fantastic plays especially by Blizo and Chunli. Chunli had clutch crackling jade lightnings, using the knockback to peel Blizo off of his team mates. At the same time Blizo also did a fantastic job preventing his team from dying and making sure to have as high uptime as possible. If anyone on either side made a mistake in these games, it would have ended almost immediately after. That is fast pacing, while still reaching dampening.
The current meta is quite the opposite though. Even if you fight a team that is absolutely inferior to yours, you will still have the game reach dampening. No matter the mistakes on the other side or good set ups on yours, you just will not have kill pressure. This is slow pacing. Even if a kill happens quickly, say from a Boomkins Incarn - that doesn’t necessarily mean the pacing was fast. When games will by default only end in dampening it is slow.
I recall recently playing with my team mates Kaska and Syfoxy. We faced against an FPS, that was around 2500 MMR. Since we were on our alts, we were about that same rating. From the first minute of the game, I absolutely knew we won. We were constantly in the winning position, the enemy was always behind, and there was no threat of us losing. The enemy was probably gladiatorish experience, compared to us as Multi R1s with average tournament success. It took 12 minutes for the game to end, even though I knew we had won based on how the game started out. We always had momentum, I knew the team wasn’t as experienced and it was only a matter of time before we won.
Pacing like this isn’t all too common in the current patch. There’s no reason to play any burst oriented comp, I would say it should always be some double melee comp that’s tanky and has potential to get kills in dampening, or some defensive wizard composition. Either way, games will be long and there’s not much you can do about that.
I think good pacing is when damage is high enough and scary enough that you can win when someone makes a mistake, but games can still be long and back and forth because of the option to outplay those kill windows. When pacing is slow, you will always struggle even when your opponents make those defensive mistakes, taking excitement out of the match. I personally think if I’m fighting a team I know is less experienced than myself, and I know the game is already win, it should end in a minute. It’s good for us because we can quickly get out of a bracket where we fight that team and move onto the next game, and good for our opponent to be put out of their misery quickly. A slow paced meta can give the losing team false hope only to be dissappointed when they lose. It also prevents that team from quickly escaping their MMR bracket, opening up for another miserable defeat.
Hopefully that explains it enough