Yeah, also interesting stuff. And more just for the curiosity - I tried to wrap the FileWriter by BufferedWriter ( http://download.oracle.com/javase/6/docs/api/java/io/BufferedWriter.html ) in your test and to no surprise the result also became very close to BufferedOutputStream. Following results are from 2nd runs within the JVM instance as first runs are (as usually) a little more "biased": Java 6: FileOutputStream: 7186 BufferedOutputStream: 613 FileWriter: 713 BufferedWriter/FileWriter: 625 Java 1.5: FileOutputStream: 7765 BufferedOutputStream: 955 FileWriter: 1131 BufferedWriter/FileWriter: 918 Looks like the use of FileWriter itself is a decent option while adding buffering always helps at least a little. Also funny that BufferedWriter around FileWriter performs consistently better than BufferedOutputStream at Java 1.5 while at Java 6 it's exactly the opposite (but here the difference is minor).