Is Tectonic a mod or a datapack?
Tectonic is available both as a mod (Fabric, Forge, NeoForge and Quilt from 1.18.2+) and as a datapack, with releases going back to 1.18.2, so you can use it on any Modloader, or just enable the datapack during world creation from 1.18.2 onward.
Does Tectonic cause lag in Minecraft?
Tectonic reshapes terrain (continents, deep oceans, massive ranges), so its main impact is during world generation and exploration. If you see slow chunk generation or stutter try pregenerating chunks (e.g., with the Chunky mod), lowering render and simulation distance, or reducing the quantity of other worldgen mods you have.
What is Tectonic?
Tectonic is a world-generation project that overhauls terrain shaping, adding continent-scale landmasses, deeper oceans, long mountain ranges that approach the build limit, underground rivers/lava tunnels, canyons, dunes, plateaus, valleys, wetlands, and more. The mod version has a config file and in-game config screen.