Searched the Houdini documentation found nothing (big surprise lol) on what this green glowing means. Screen shot is attached. Thanks!

I think it indicates your fuel is 3/4 full.

Just kidding, sorry, just had to say it

I'm going to guess that at some point you had the performance monitor profiling and only those 3 nodes ran.

The glow indicates how significant, relative to the node that took the most time, the amount of time is for a particular node. That said, I'd expect it to be either quite a thin glow, or red instead of green, but maybe there's some setting to change those, or maybe there's something amiss with high DPI monitors where it's stretched out the green glow that's normally much thinner. Maybe there's something else that uses the glow too, but that's my best guess.

Thank-you! I was trying to remember where I had seen that before and under what circumstances but when I searched the documentation nothing showed up. I am pretty certain from your post that its related to performance monitoring and will look in that direction.

Update:

I made certain that performance monitoring was turned off, created a curve and applied a pyro fire effect to it and the green glow appears.

Network Editor Display Option/ Dependency -> Show Time Dependencies

Artye
Network Editor Display Option/ Dependency -> Show Time Dependencies

Thank-you! That was the answer.