quickest way to get from paris to barcelona airport

Check Vueling Air flights between Barcelona and Paris. Assuming you'll spend some time in Barcelona after you arrive. You may want to return to Barcelona the night before your departure to the states to avoid any "hiccups" in getting home.

Your best bet would be on EasyJet.com out of Paris DeGaulle Airport or Vueling out of Paris Orly Airport. They're both a couple of the best budget air carriers in Europe. Check and see which flight schedule bests suits your schedule. Most people are now booking tickets open jaw into one city and out of another to avoid backtracking which is expensive.
I would never book a flight into Barcelona on a budget air carrier the morning of my departure home. Miss a flight or have a delay for any reason and rebooking your flight would be enormously expensive. Give yourself more time leeway.

I think you would find flying to be the fastest way between Barcelona and Paris. You can use a website like www.edreams.com to find all the possible flights between the two cities. Note that the discount airlines may use airports which are smaller or farther from the city than the larger airlines - Gironda airport instead of Barcelona for example or they may fly to Orly instead of Charles de Gaulle. They also have very restrictive luggage rules so check those rules carefully.

Well flying out of Orly is absolutely fine, as is CDG , both are good airports to use, I would however avoid using Ryanair as they use Beauvais airport which is 1.5 hrs from Paris and no direct route, must bus and train it.
We used Easyjet last summer and it was fine. I have used Vueling twice before and like them too.