Download an offline-launcher-compatible version of Minecraft (or use the official launcher with -Djava.net.preferIPv4Stack=true for cracked compatibility). Find a cracked speedrun server with a /reset command. Practice The End fight until you can do it blindfolded.

You will reset faster, lag less, and improve quicker.

If you are currently trying to improve your Fortress split time on a laggy premium hub, you are holding yourself back.