What is cache uniform expressions ?

Hi,guys,I’m so confused by this Cache uniform EXpressions thing in the CPU profiling.
What are Cache Uniform Expressions including? What does that stand for?
If I want to decrease this value, what should I do?

Uniform expression cache is a system, that analyzes material graph, detects parts of it, that are uniform(that is, having the same value for all the pixels or vertices), removes them from material and replaces with a single parameter, value of which is evaluated and updated as needed. And the time you are seeing is the time spent updating all such values in your scene.


Thank you for clarifying this to me as well. Your comment is very helpful.

So uniform expression cache explains the complexity of material? The simpler the material is ,the less time it takes?