Hello, i am regarding pasting schematics in a world, when I try to paste them in using the "paste schematic in world" mode on singleplayer, it does it all in one go and quickly, however when I try it on my server it goes bit by bit , does anyone know how to change this?

This is not an issue with the mod. You can ask for help in the discord.

Generally, when pasting on a server; it has to do it via "Command Spam" in order to place all of the blocks; because you don't have direct server access from your client.

Newer versions of Servux (0.3.X) can do this for 1.21, though.