Cyrogenic treatment for CD's?

I have been treating CDs and other audio related items cryogenically for around fifteen years.

Sonically there's some improvement in smoothness and transparency.

Cryogenic treatment has value for improving structure/electrical conductance of metals so long as you don't undo it by disordering the metal structure later by heating it. Of value for wire, dubious for tubes that heat red hot.
CD's are a reflective metal film read by laser optics, not by applying voltages so no value there.
If you want to improve a CD use something like Stoplight that damps edge refracted light which can cause errors in CD reading. CD's can also film/scratch so that polishing kits can restore a degraded CD. Ring labels can help stabilize the transport horizontal axis reducing jitter as the optics read closer to the outside radius of a CD.

There are at least two ways that cryo improves CDs. First, it makes the CD stiffer and less prone to vibration by improving the physical characteristics of the metal layer and the clear layer. Second, it improves the physical characteristics of the clear layer, making the laser reading more accurate.

Heat treatment is also tempering, like cryo, and actually improves the physical characteristics of metals. This is why tools and swords and such are heat tempered - for better durability and strength.