There are traits, events that could increase move speed. But 10 for all civs is excessive.
The AI gets bonuses at higher difficulties, but only at Incredible and up would these really affect move speeds.
I suggest you verify integrity of game files. To verify cache integrity right click on a game in your Steam library, Properties, Local files tab and then click the Verify integrity of game files.
If the problem persists please upload a save game and post it here so someone could take a look at it.