One track + One chord = stuttered playback

New PC Win 10 64 bit - i7 - 32G RAM
Cubase 10
Buffer 256 samples
Interface UR44

One virtual instrument track from EZ Keys playing one sustained chord for about 10 seconds. It stutters in playback every few seconds.
Same with Halion synth, one track in the project, I play and hold one note and the output I’m hearing stutters and farts like a car running out of fuel. Totally unusable at this point. Tried with direct monitoring on and off, no change.
Any ideas why this is happening?

Seemed to have solved the problem but not sure how. Could have been having the standalone player/s running as well as the midi track.

I notice that when I add a block of midi notes to a virtual instrument track, a midi track named SysEx Data is always created. Doesn’t seem to do anything or have anything in it. I will research this further.

Glad I’ve got smooth output now.