Latency jumps but why?

You can run MIDI Guitar standalone: [blog] Clever ways to optimize your plugin usage - #2 by npudar

I’d try first that.

In the instances way, in the second instance, I’d try with a different driver – FlexASIO or ASIO2WASAPI to see are there any improvements.

Also, in this particular setup, I wouldn’t go with the buffer of 128, but 64 (if possible).

I personally work with 128, but I use simple setups, there is not much things going around.