In the documentation for the Prudent property of FileAppender (http://logback.qos.ch/manual/appenders.html#prudent), 100'000 is incorrectly entered as 100'00 (missing a zero):

"...when prudent mode is off, it takes about 10 microseconds to write a single logging event. ... This translates to logging throughput of 100'00 events per second..."

I'm not sure if the following comment is being too pedantic, but the section also sates that with prudent mode on, it takes 30 microseconds to log, which translates to 30'000 events per second. 30 microseconds would be 33'333 events per second. I'm not sure if that is a typo or just an approximation. If it is the latter, it might be helpful to add the such verbiage:

"...and approximately 30,000 events per second."

Alternatively, using the 33,333 value would make the 3x cost more apparent I think.