Wild creatures (and NPC's) movement speed is based on DEX and their current Stamina %. This is capped at 190 on tamed pets, but it's not capped on wild creatures/NPCs. High Wave # Pirates have incredibly high stats and skills, so they move extremely fast.
But this, at least for me, becomes an issue at some point because I do not even have the time to cast invisibility on myself (using Protection for obvious reasons) to break Pirates aggro on me, they catch up with me in no time and, with higher waves, they can kill me pretty fast before I can cast invisibility on myself.
I also noticed that, those rare times that I can cast invisibility on myself before the Pirates catch up with me (at waves like 40-45+) too often I get revealed and then killed. Also, their aggro on me seems to be very hard to be interrupted, only if I am able to stay hidden for some time and not get revealed and they switch target, then I can unhide.
I also noticed that, if I cast area spells which do damage to the Pirates (for example Poison fields or Wildfire), even if there is other players, pets or summons attacking the Pirates and nearer to the Pirate then where I am, they usually stick their aggro on me and even if I run away they disregard the other players/pets/summons attacking them and closer to them and keep running instead after me.
I am not sure why this happens... with other MOBs they usually stick with their nearest attacker whether it was to be a PC, a pet or a Summon... at the Void Pool, instead, say that there is a Triton fighting several Pirates toe to toe, I cast from a distance an area spell be it Wildfire or Poison field (I am much farther as to where the Triton is), immediately one or more Pirates stop fighting the Triton that is right by them and come after my character who is several tiles away from the group.
What gives ? This makes it very difficult, because of their superior speed, to then have my character stay alive.
Bottom line is, I noticed, that at higher waves I almost inevitably end up dead in order to break a Pirate aggro on me and this can be an issue since at higher waves it is not easy to get another player's attention and get a resurrection, everybody is usually in trouble and trying to break Pirates aggro on themselves to be able to stop and resurrect a fellow player.
Personally, I think that it should be made easier to break Pirates aggro on players' characters... as it is now, Pirates stick on players' character and it is very hard to break this aggro and it usually ends up with the player's character ending up dead, at higher waves.
For example, if Pirates at the Void Pool were to be set as their priority to focus on Pets on Summons when nearby, rather then players' characters, this could give a little help to players to break Pirates' aggro on their characters.
Or is there a better way which I have yet to find to break Pirates' aggro on a player's character at the Void Pool ?