While WoW Classic players continue to hold their breath as to what Blizzard has planned for the legacy version of the game, they are seeing one significant change in the works. Right now on the test server, the studio is testing a change that takes the spell batch window from 400 milliseconds down to 10 milliseconds.
Spell batching is a way that World of Warcraft handles organizing and executing all of the incoming interactions from players (such as spells and skills). World of Warcraft back in 2004 had a longer spell batching window to allow for slower tech, where groups of spells would be executed simultaneously. So when Blizz made WoW Classic, it artificially reinstated this longer spell batch window to simulate how the game used to perform. As such, spell batching has been a hot-button topic ever since the MMO came out.
But once the next patch hits, spells are going to fire off in the order they were activated with a largely reduced chance of, say, two players’ abilities being processed simultaneously. This will have the biggest effect on WoW Classic’s PvP battlegrounds and PvE raids.