What is better to use when there is no difference in technical terms - static methods or class instances?

Question

PHP

Good afternoon.
We are talking about, for example, models that contain only self-sufficient functions that do not contact each other in any way, or libraries of functions. Create a new instance before calling, or just make all methods static - wouldn't the latter be faster and better? In architectural terms, there is no difference, because. the two approaches are interchangeable in this case .
Thanks in advance for your advice!

Answer 1

In architectural terms, there is no difference, because. the two approaches are interchangeable in this case.

This is not true. Static classes are evil.
A huge disadvantage of static classes is tight cohesion.
This masks the dependencies.
This forces you to change the code instead of providing an object of the same type (but different).
This complicates the tests.
It is a "global variable" among classes.
Reason enough?

Answer 2

Read (don't skim, just read) Martin's Clean Code, McConnell's Perfect Code, Gang of Four Design Patterns.
Then you stop asking such dubious questions.