asyncio:

    import time
    import asyncio

    REPS = 1_000_000

    async def coro():
        for i in range(REPS):
            await asyncio.sleep(0)

    t0 = time.perf_counter()
    asyncio.run(coro())
    dt = time.perf_counter() - t0
    print(REPS / dt, 'reps/s')

asynker (https://github.com/enkore/asynker):

    import time
    import asynker

    REPS = 1_000_000

    async def coro():
        for i in range(REPS):
            await asynker.suspend()

    t0 = time.perf_counter()
    sched = asynker.Scheduler()
    sched.run_until_complete(coro())
    dt = time.perf_counter() - t0
    print(REPS / dt, 'reps/s')

The excellent curio (https://github.com/dabeaz/curio):

    import time
    import curio

    REPS = 1_000_000

    async def coro():
        for i in range(REPS):
            await curio.sleep(0)

    t0 = time.perf_counter()
    curio.run(coro())
    dt = time.perf_counter() - t0
    print(REPS / dt, 'reps/s')

Not that this number is hugely important.