Lithium 0.12.1 is the first release for 1.20.3.
You can check out all configuration options at description of all optimizations here.
Full Changelog: mc1.20.2-0.12.0...mc1.20.3-0.12.1
Additions
- Very experimental item entity optimizations (disabled by default for now)
- Caching of block class analysis, reducing startup times