There's a difference between "the compiler is faster when run at the CLI" and "the language server is faster". A good language server remains responsive by doing quick, partial compilations on just the section that changed. A bad language server just wraps the standard compiler and re-runs the whole thing when a file is saved. The latter will eat up CPU/RAM and make for a frustrating dev experience, no matter how relatively-fast the base compilation time is.
OCaml (the Reason compiler) has historically had excellent (and fast) editor support tooling: Merlin.[1] That is now being packaged up as a language server (i.e., LSP).[2] Once you try a Merlin-based editor addon, everything else will seem dog-slow.
The standard compiler can do a cold compile of a single file in milliseconds. When the compiler is that fast you _can_ just wrap it up and it'll still be faster than TypeScript.
But to answer your actual question:
The current standard (reason-language-server) does simply wrap the compiler, and it's more than fast enough, but the community is working on a new merlin-based language server (ocaml-lsp) which does support partial compilation.
I used to use IntelliJ, and there was a solid plugin for that as well.
ReasonML's compiler is way faster than Typescript's.