If seeing the PortableApps splash screen every single time you launch Portable Firefox gets on your nerves, you aren't alone, and thankfully there's a quick and easy solution to your problem.
Over at the How-To Geek site (my home away from Lifehacker), writer Mysticgeek writes up a guide to killing the splash screen in PortableApps applications, which requires nothing more than a simple file edit. To make the change for yourself, you can find the INI file in the OtherSource directory, change the DisableSplashScreen line to False instead of True, and the copy the file into the same directory as the executable file. Hit the link for the full walk-through for Firefox Portable, but the same method should work for any of the PortableApps.com applications.
If you're a beginner to the world of portable applications, be sure to check out our five best portable app suites, the five best portable applications, and our guide to using Dropbox for more than just file syncing—it's also a great place to store your portable applications.