Ah, I beg your pardon.
The latest Jetpack release is 4.6.3/L4T 32.7.3 but the only changes there are security fixes which would not improve performance.
Let me ask you and Nvidia a question:
Please could nvidia provide nvargussrc with a reduced or customisable buffer queue size?
According to this post Nvidia has done that in the past with a similar plugin:
It would greatly improve my product if you could do this because at present the nvargussrc gstreamer plugin is poorly optimised.