A PC running an older or lower-end CPU (ex. You may have noticed that Minecraft uses 100% of your CPU when it loads into the title screen. This can cause cursor stuttering and make multitasking difficult. Smooth Boot Mod (1.18.12) fixes this issue completely. Loading should be smoother and possibly faster. Optimize Minecraft loading performance for smoother operation on low-end systems, and better scaling on high-end systems.
Minecraft uses executors for multithreaded tasks. Problem is that tasks that are run during loading can be very heavy on the CPU. This causes 100% CPU usage. Multithreading is not always beneficial for all tasks. Smooth Boot solves these problems by changing the parameters of executors such as the number of threads used and the priority of each thread.
All mods, including and Optifine, should work with the mod. It is worth noting, however, that the mod uses mixin-overwrites for some methods of loading the game.