Smooth Boot (Reloaded) is an optimization mod and unofficial Forge fork of Smooth Boot. It fixes the 100% CPU usage that Minecraft causes while loading to the title screen, which brings cursor stutter and makes multitasking painful, so startup feels smoother and can even be faster.
You can change how many threads are used for loading and set their priority. It supports Forge on Minecraft 1.18.2 - 1.20.1 and is no longer maintained. Building a Forge modpack for your Minecraft server? Smooth Boot (Reloaded) installs from the panel in one click.