FVWM with Nautilus? And what are you trying to do, run Konqueror in Gnome? The point is once you give up Gnome or KDE, you've also got to give up those programs, otherwise you see little benefit in using a lightweight window manager. For me, a window manager launches three GUI programs: Firefox, Openoffice, and Emacs. Each use a different toolkit; only Firefox's startup would be marginally faster had I used Gnome. Openoffice uses its own toolkit. Emacs uses Xaw3d. The fourth X program I run is rxvt. Now, when you're window manager does little else but manage an array of terminals, you begin to appreciate how much faster it is compared to a desktop.
KDE and Gnome try to emulate Windows. Using a lightweight window manager and KDE/Gnome programs still tries to emulate Windows. Use the command line, man! That will take care of nautilus and konqueror and k3b. XMMS is very fast, thus only Firefox in unavoidable.