Jetty Locking Files on Windows

I went to edit a css file today on a server an OpenBD Jetty install and the file was locked. After doing some research I found this http://docs.codehaus.org/display/JETTY/Files+locked+on+Windows

I chose to just stop and restart Jetty because I was on a dev box. The instructions seem to be straight forward.

My question is though. If I disable the memory mapped files will there a performance degradation?