Messages written to graph log are checked before writing to the graph log file. If any password is detected, it's masked by some stars: ******
This is done by a pattern that is very slow for larger inputs.
I've run into this problem when using jms event listerer starting a graph. My JMS messages can be large (60KB). Content of messages is passed to graph in a graph parameter. The parameters are logged to graph log at graph start and that causes the slowdown.
It takes 2 minutes (!!!) before my graph is started after the jms listener receives a message.