how big is the performance hit to map all requests to asp.net worker?

[alex]

how big is the performance hit to map all requests to asp.net worker
process?

like file extention .* to be handled by the worker

considering my app already handles .htm file by the asp.net, so there
are images, js, css left..

and btw when u do that default documents no longer work, any way to fix
it?

anyone?

tnx