That's fair I guess. In the case of IO that can be an issue. When I hear multicore, I assume we're talking about parallelism, not concurrency.

As for LSP, other than the Nim langserver, I've been quite satisfied with Eglot's performance. I'm curious what your setup is like. To be fair, I'm running a highly customized Doom Emacs config, so it's possible I inherited some non-vanilla optimizations I'm not aware of.

> When I hear multicore, I assume we're talking about parallelism, not concurrency.

Parallelism trivially enables concurrency. The lack of parallelism magnifies the issues emacs has with concurrency.