Basically, it's a mix of Optifine and most of the modern optimization fabric mods, like Sodium and Lithium...

Also, most of the mods are client-side! (98% of them are client-side)

• Also, you can replicate the trailer's graphics!
• Aaaand, with the Nostalgic Tweaks (client-side) and the Golden Days Resource Pack (or the Programmer Art Ultimate), you can replicate the old and nostalgic graphic of Minecraft!
• Infinite Delay Music!
• The chat is more manageable!
• Voice Chat! (if you got some friends, you can talk with the Proximity Chat Voice, which is cool, I think...?)

Thanks to all the modders and resource pack-ers!