java regex

I wrote a regular expression , which determines whether the string contains " _4 digits . Csv" string , but if the characters found containing " _5 numbers . Csv" , the program runs very slowly , please help me look , I do not have much experience of regular expressions , poorly written , if you can optimize it, please help me to optimize what bigwigs .

  import java.util.regex.Pattern;
  
  public class Test {
  
  	/**
  	 * @param args
  	 */
  	public static void main(String[] args) {
  		// TODO Auto-generated method stub
  		String str = "20131210_19045.csv,a.csv,";		
  		System.out.println(""+Pattern.matches("(\\w*?\\W*?)*?(\\w?_\\d{4}.csv,)+(\\w*?\\W*?)*?", str));
  	}
  
  }

------ Solution ------------------------------------- -------
try this

			String str = "20131210_19015.csv,a.csv,";
  			System.out.println(""+Pattern.matches(".*(?<=_)(\\d{4})(?=.csv).*", str));

------ Solution ------------------------------------- -------
. *? _ \ \ d {4} \ \. csv. *
------ Solution -------------- ------------------------------

  String str = "20131210_19045.csv,a.csv,";       
  System.out.println(str.matches(".*_\\d{4}\\.csv.*"));
  

------ Solution ---- ----------------------------------------

	@Test
  	public void test()
  	{
  		String str = "20131210_19015.csv,a.csv,";    
  		System.out.println(""+Pattern.matches(".*_\\d{4,}+\\.csv.*", str));
  	}

Although successful , but the feeling is still slow. . .