Welcome to the LMMS Wiki! Here you'll find the documentation, tutorials, guides, resources, and much more.
Manual [wiki] [pdf] (for v0.4.12)
How to Report Bugs
Developers (Wiki on GitHub)
Creating a Theme
Theme Porting Guide
If you find that your song is eating too much CPU you can export the song as a .wav and import it back using an sample track or AudioFileProcessor, this will bring the CPU load down and give room for more instruments, effects and automation tracks.