What are the performance benefits wrt compile-time binding when we use SLF4J or Log4J in Spring instead of JCL?

Question

Spring documentations states:

SLF4J is a cleaner dependency and more efficient at runtime than commons-logging because it uses compile-time bindings instead of runtime discovery of the other logging frameworks it integrates.

Allegedly there is also a performance benefit because the bindings are at compile-time not runtime.

What exactly does this compile time binding mean here? And how does it impact the performance?