How to optimise VFX exlposion?

I have a an explosion of sort and it looks great however, When I (the player) walk too close to the explosion and it fills up a lot of the screen the fps suffers a lot, dropping from around 140 to 17. I'm guessing this is due to having to fill up a larger portion of the screen but what sort of things should i be looking at to optimise this without effecting too much how it looks or it's size?

I have a HDRP scene with volumetric fog/lighting. The VFX is set up currently t output a Lit Quad with a Translucent material type. This set up just looks right in the scene but I'm willing to compromise where I can for performance of-course.

Any advice would be super appreciated.

Thanks,

 

Thanks buddy that's actually helped a lot. you gave me the right direction to go in and I did a bit more research and now its not dropping below 60 fps. I do think I can do better though.

Thanks again