Mike Schilli mentions 30K ops/sec by an "in-memory" appender, which sounds high for something writing to disk. Call me a tad skeptical on this claim (perhaps it is a measurement of the library's efficiency sans disk writing).

An "in-memory" appender means exactly what it sounds like it means. It's not writing to disk, it's keeping the log entries in memory. If your performance concern is with the speed that log entries can be written to disk, there are plenty of alternatives to simple logfiles:

• Log::Log4perl::Appender::Spread - Log to a spread cluster
• Log::Log4perl::Appender::Jabber - Log to jabber
• Log::Log4perl::Appender::DBI - Log to a database
• Log::Log4perl::Appender::STOMP - Log to a message queue (such as POE::Component::MessageQueue)