In edit mode select side faces and assign material with Emision Shader.
This glass plate consists from three materials:
front/back side with Glass Shader
bottom side with Emission Shader
top/left/right side with Glass Shader but now with Roughness 1
I'm not super happy with this one, but when it comes down to it you might have to fiddle around with just about any solution that's given to you. It's kind of the nature of procedural generation, so here goes.
This is based on another answer I did over here:
Sine wave on the environment texture
You can read through that for the whole discussion on this. ...
First, the initial results are good.
I would say don't connect the same thing to both normal sockets. Do use the clearcoat normal (and I'm a fan of including whatever level of microdetail you want) but consider mixing in much larger scale imperfection as well, to try and coax this type of imperfect reflection from the clearcoat layer.
Make another bump ...
You can achieve an effect like this by manipulating the normal.
Here's Suzanne showing the difference with the default surface Normal and the manipulated Normal based on the vector from the origin to the surface point :
By using a Normal calculated based on the origin, the reflection will always be as if it is formed on the surface of a sphere - thereby ...
Close to 2 million faces, high levels of subdivision surface modifiers, large textures 2K and 4k... all of that uses resources from your computer and eventually you will run out of them.
Why does Blender use so much memory for large textures?
Using 4k textures on something that will only be a few hundred pixels tall on the screen is wasteful.
Every step you listed except for clamping probably helped out.
Turning clamping to 0 actually unclamps them completely. You need some value in there, I think indirect is clamped at 10 by default and unclamping it increases render times pretty significantly. It probably wiped out all the gains made by the other methods.
As for the memory usage, check your ...