KAL is an Intel Pentium 4 clocked at 2.53 GHz running XP and Sun's JDK 1.4.1.

Results are in microseconds.

Tests are based on new LocationInfo extraction code optimized for JDK
1.4 and later. Note the significant improvement in speed wrt to
location info extraction.

NullAppender:

   3.97 PatternLayout "%p - %m%n"
   3.87 PatternLayout "%-5p - %m%n"
  10.68 PatternLayout "%r [%t] %-5p %c{2} %x - %m%n"
  10.48 PatternLayout "%r [%t] %-5p %.10c %x - %m%n"
  10.41 PatternLayout "%r [%t] %-5p %.20c %x - %m%n"
   9.18 PatternLayout "%r [%t] %-5p %c - %m%n"
  17.92 PatternLayout "%d{ISO8601} [%t] %-5p %c %x - %m%n"
  17.92 PatternLayout "%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] %-5p %c %x - %m%n"
  68.13 PatternLayout "%l - %m%n"        
  75.67 PatternLayout "%C.%M.%L - %m%n"

FileAppender:

  10.41 PatternLayout "%p - %m%n"					   
  10.34 PatternLayout "%-5p - %m%n"					   
  22.16 PatternLayout "%r [%t] %-5p %c{2} %x - %m%n"			   
  18.39 PatternLayout "%r [%t] %-5p %.10c %x - %m%n"			   
  18.72 PatternLayout "%r [%t] %-5p %.20c %x - %m%n"			   
  17.42 PatternLayout "%r [%t] %-5p %c - %m%n"				   
  28.61 PatternLayout "%d{ISO8601} [%t] %-5p %c %x - %m%n"		   
  27.94 PatternLayout "%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] %-5p %c %x - %m%n"
  87.69 PatternLayout "%l - %m%n"					   
  93.16 PatternLayout "%C.%M.%L - %m%n"                                     

FileAppender: (ImmediateFlush=false)

   5.80 PatternLayout "%p - %m%n"					   
   5.87 PatternLayout "%-5p - %m%n"					   
  13.82 PatternLayout "%r [%t] %-5p %c{2} %x - %m%n"			   
  13.48 PatternLayout "%r [%t] %-5p %.10c %x - %m%n"			   
  13.82 PatternLayout "%r [%t] %-5p %.20c %x - %m%n"			   
  12.75 PatternLayout "%r [%t] %-5p %c - %m%n"				   
  23.03 PatternLayout "%d{ISO8601} [%t] %-5p %c %x - %m%n"		   
  22.46 PatternLayout "%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] %-5p %c %x - %m%n"
  81.98 PatternLayout "%l - %m%n"					   
  88.12 PatternLayout "%C.%M.%L - %m%n"                                     

FileAppender: (BufferedIO=true)

   5.74 PatternLayout "%p - %m%n"					   
   5.84 PatternLayout "%-5p - %m%n"					   
  13.85 PatternLayout "%r [%t] %-5p %c{2} %x - %m%n"			   
  13.61 PatternLayout "%r [%t] %-5p %.10c %x - %m%n"			   
  13.62 PatternLayout "%r [%t] %-5p %.20c %x - %m%n"			   
  12.18 PatternLayout "%r [%t] %-5p %c - %m%n"				   
  21.83 PatternLayout "%d{ISO8601} [%t] %-5p %c %x - %m%n"		   
  22.1] PatternLayout "%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] %-5p %c %x - %m%n"
  81.01 PatternLayout "%l - %m%n"					   
  87.79 PatternLayout "%C.%M.%L - %m%n"                                     



Notice the small but noticable performance gain when
ImmediateFlush=false

Note also that BufferedIO yeilds similar performance to the
ImmediateFlush case.