I revive this old post now since we are back from vacation and have started catching up on the SVG part of things.
We managed to solve our issues with the SVG not being visible at least (basically by simplifying everything), BUT, I see some performance issues when rendering these files.
Basically I made a simple implementation of a rotary slider (knob) using SVGs (through custom look and feel as advised).
The SVG itself is quite small and simple (about 8kb file size).
I then added about 240 of these knobs horizontally inside a viewport with a horizontal scrollbar, I then animated the sizes of the knobs from their original size to about 10x so that I go from having 20 visible knobs to about 2 and this made the performance drop like crazy. I have a timer doing the repaint at 60hz and with 20 knobs visible i have a steady 60fps but when scaling them up to the point of having only 1 or 2 visible, the fps drops to around 35-40fps.
I dont know if im using it wrong, something in the JUCE renderer is wrong, or if this is just how it is?
Running the JUCE demo project with the SVG render demo shows similar effects when scaling up so I dont think im using it wrong (or the demo does it wrong as well :) )
Edit: I just noticed that this happens even with the default look and feel's rotary slider!