Surprisingly, Eaglercraft 1.21.1 runs smoother than earlier versions. Thanks to better WebGL rendering and optimized chunk loading, you can get 60+ FPS on a Chromebook from 2020.
If you are playing a community port of 1.21.1, it likely aims to include these standard Minecraft 1.21 features: Trial Chambers eaglercraft 121 1
: Because these builds are experimental, single-player worlds may become corrupted between updates. Always back up your world files. Next Steps Surprisingly, Eaglercraft 1
: Some specialized clients, such as Tuff Client , have been reported to support 1.21 texture packs on Eaglercraft, allowing players to see modern entities even on older underlying versions. Gameplay and Server Features such as Tuff Client