Fishu my first GB empire ended the same way. I had not killed France or Spain and their navy/army was so large it made each turn take 15 minutes for the CPU to think. Second time round i marched from Gibralta to Paris in the first 15 turns. Game has been running alot smoother without those two factions, and a loss in Europe destroys their American colonies and creates Mexico and Columbia factions.
In the first empire the Spanish navy alone is enough to crash the game at times, not to mention the 10,000 troops they had defending the Spanish mainland.