I'm using the The RunLocally entry because I use Portable Firefox on a CDRW.
Then, Firefox Portable copies my profile, plugins and Firefox binaries to my local temp directory : about 4 Mo! It's then very slow to start Firefox Portable from a CDRW.
Why not copying only the profile? It would be very quicker to start without copying plugins and Firefox binaries but using them from CDRW. Is it possible?
Firefox's directory has to be writeable. It's a limitation of Firefox itself. If it worked from the CD, it would have been left on the CD. It works this way because it has to.
Sometimes, the impossible can become possible, if you're awesome!