FOSS gamedev and creative worlds

Whenever I try to craft something like a door, it takes some time for it to update and craft the door. Whenever I try to place the door or any block, it takes it's time to place it.
Is some of the settings wrong or is my computer slow?

post your computer rig here please.

Multiplayer or singleplayer?`
Servers for multiplayer have lags from 1s up to 10s, so it's possibly not your PC's fault if you are playing on a server.