Alas they are BIG. Well, just now I am up to 14 outputs.
Recently when I open them, scrolling inside them is painful.
From memory the list starts at the bottom, but either way:
I want to get to the other end.
I start to scroll with the MMB.
So, I scroll and get to the other end of the list.
As soon as I stop, it jumps back to the original end of the list.
This happens for about 4 tries then it finally obeys me and stays scrolled at the other end.
Bug?
It is not really practical sending in screen shots. It is a dynamic thing that won't really be seen with pictures.
There was a nice initiative few weeks ago to improve the rendering of the switch node.
I guess this improvement is already available in the latest release of Node-RED. At least I don´t perceive slowness in a testing switch with 21 outputs. Also I never noticed the behavior you mentioned in your post. This leads me to ask you the very well known question: in which version of Node-RED you are perceiving the issue ?