Threads are defined by a shared address space, so ithreads are not threads in the first place. Many people (including you) confuse them with real threads (as implemented by Coro),

Utter, unmitigated & unmitigatable, ridiculously uninformed or knowingly deceitful, grade-A, four-star baloney.

Threads are defined by two things: shared memory and concurrency.

Coro fails to meet this fundamental definition because it doesn't do concurrency.

It also cannot make use of multiple cores, and so cannot be used to speed up process intensive processing (like matrix multiplication!). Your benchmark is garbage and your words either naively & hopelessly misinformed; or deliberately misleading.