I understood - if i have small trafic, i don't need use a cach posibilities, if my site have a big trafic - better is using this function. Is it correct?
You can say so, this is the general idea. But there is a hidden issue here: sometimes if cache files are too much it is better to load the content from the database rather than searching the huge cache directory to find the proper cached files. But this depends on many things.