Upon examining the game binary's (Linux) running with lsof, I found it is not holding the chat log file open. I can only presume it is opening and closing it with each write. While I know this affects Linux, I suspect it affects Windows as well. This introduces several performance issues: 1. Creation and destruction of file handles with each write and thus creating GC load, and possible memory leaks. 2. No active file handle, resulting in poor OS file handling performance. 3. Synchronizing file output on close, even if written in async mode, freezing world thread until the write is completed. The last one is the greatest hit resulting in 75-250ms of world freeze on a rotational disk for each chat message logged to disk. Note that this includes each looting message, and each combat hit. There are two possible solutions: 1. Create a pipe to file for handling chat logging. 2. Use an Asynchronous buffer for chat logging. For option number two I recommend using a good 8MB buffer and very low sync frequency. This will reduce log write frequency further improving performance. Option one will rely on the OS, and thus you simply don't have to worry about it.