my guess is alongside with the hdri lighting, then the other lighting. and asuming you have raytracing. Ye that i`ll explain the rendering time.
I would suggest as for any other project your doing, start with one main light, then add more lights. This way you see what happens for every light and also the render time.
Also because your objects are glass, the refractions are also heavy for rendering.
So now in general you gotha start thinking, ok what is my final image going to be, a close up? Just from far in full?
For these objects i think you can get good results without using hdri lighting, you would get a good result using a dome.
So if its far try to reduce the refractions to 1
if its close try starting from 1 then upwards.
Also try to see the difference between shadowmaps and raytracing.
Try to switch off GI and FG
So the important thing of working is knowing what you want in the end. And doing the renders step by step.
Anyways thats what i have learned, and helps me get nice results