Exactly how slow are C, F, L, l and M of PatternLayout (log4j)?

Question

It\'s common knowledge that C, F, L, l and M of PatternLayout are slow:

WARNING Gener

Answer 1

I measured locally on my computer using a FileAppender. I warmed up the test nicely, measured many executions and averaged the (relatively consistent) results. The loop contained execs++;log.info("t");The exact numbers do not matter (because they depend on my computer) but proportions do. I used log4j-1.2.16.jar on Java 1.6.0_10 (Client VM).

It turns out that whenever any of the C, F, L, l or M appeared in the pattern, logging was at least 5 times slower.