A useful piece of software to work with to get further information here is LatencyMon - which might be worth playing with - with and without loopMIDI and with or without any drivers that it installed (such as virtualMIDI).
A useful piece of software to work with to get further information here is LatencyMon - which might be worth playing with - with and without loopMIDI and with or without any drivers that it installed (such as virtualMIDI).