Ideally the cost of a coroutine call should be comparable to the cost of an indirect function call. Currently Boost.Coroutine, at least on Linux-x86-GCC come close to 150% of the speed of Boost.Function, itself comparable to the cost of an indirect function call. The Win32 implementation has not been benchmarked, but it might be slightly slower because of the need to switch exception contexts and some missed optimization opportunities. The makecontext based implementation is at least three orders of magnitude slower than the others due to the need to perform a system call per context switch.

To get good performance on Win32 systems, a call to ConvertThreadToFiber should be performed on each thread that will invoke coroutines. Else a much slower code path will be used that may potentially make context switches extremely expensive.