Efficiently encode String to Stream

I am currently using the following snippet to write an UTF8 encoded string to a network stream in a performance critical section:

private static readonly ArrayPool<byte> POOL = ArrayPool<byte>.Shared;

private static readonly Encoding ENCODING = Encoding.UTF8;

private async ValueTask Write(string text)
{
    var length = ENCODING.GetByteCount(text);

    var buffer = POOL.Rent(length);

    try 
    { 
        ENCODING.GetBytes(text, 0, length, buffer, 0);

        await OutputStream.WriteAsync(buffer.AsMemory(0, length)).ConfigureAwait(false);
    }
    finally
    {
        POOL.Return(buffer);
    }
}

My feeling is that this can be written more efficiently and maybe even allocation free using one of the Span<T> and Memory<T> based overloads, but I fail to see how.

My understanding would be that I can somehow convert the Span<char> representation of the string on the fly into something that I can pass to the stream (e.g. ReadOnlyMemory<byte> without the need to use an intermediate buffer (neither allocated nor rented) - so just by accessing the underlying bytes of the string (there is already memory allocated for them - why would I need to allocate new?).