Casual users and non-debugger users who care about this performance hit should not install the debugger, or should use a Netscape release. If we don't enable init-at-startup by default, real debugger users suffer. This *was* off by default, and folks couldn't figure out how to use the debugger as a result. The real-world performance hit isn't enough to justify turning this off. As I recall, the page load tests saw about a 1% hit. See also, http://bugzilla.mozilla.org/show_bug.cgi?id=157638#c3.