Rob Pike and the rest of the (ex)Bell Labs/Unix gang have been on both sides of this for over 20 years: both with Squeak/Alef/Limbo, then switching to using C with libthread (http://man.cat-v.org/plan_9/2/thread not to be confused with pthreads, for details see: http://swtch.com/~rsc/thread/ ), but in the end having language support for concurrency is something that is really worth it, and one of the reasons the ended up building Go.