If the renderable parameter is disabled, then the node is still cooked. And object properties can be read from the VEX shader.

Geometry Filter Width (vm_geofilterwidth) sets a minimum rendering width, in raster space, for curves and points. Any point, or curve segment, smaller than this value, at the projected point, will instead have its opacity scaled down as a ratio of the minimum width and the actual width. This helps rendering very small points and thin curves, such as hair and fur, without having to adversely increase the pixel samples to compensate. This value should be kept at around 0.5 to 1.0. Larger values may significantly increase render time, since the geometry is wider and more transparent samples may be taken. A value of 0 disables the option.

The two way switch turns off the entire branch, and it is not executed. “If” block does too. But all operators must be inside it for this.
When using the switch, all inputs are executed.

The light attenuation ramp must be used in tandem with the active radius. This gives a render time reduction of about 15 percent.

Keep in mind that normals are important for rendering when using a uniform volume. If the object does not feel the volume, and it is very dense, then you need to do a reverse.

You need to set a border = const with value = 0 for a heat field. A heat border is imported from the dynamics with a value of -0.01. This can affect shading.