I am not sure what you meant by 'SO technique.' I guess what you meant was "search engine optimization" technique.
Is your sitemap.xml for Google? Google sitemap allows a maximum of 50,000 URLs i.e. about 10MB in size. So, assuming that I was right about what you meant by 'SO', I think you have heard the wrong thing. It is 10MB not 10Kb.
One of my sites has more than 2,000 URLs and the size of the sitemap is about 720Kb.