Somabrandmayona, if it really bothers you, there is a simple fix! You could create a mod, but I just wanted it in all of my games, so just changed the core files. If you do this, you should BACK UP the file I will show you how to change.
1. Go to the following directory in your computer:
C:\Program Files\Sid Meier's Civilization V\assets\Gameplay\XML
*Note that "C:" could be any number of drive names-- whichever it is on your machine.
2. In there will be a file called "GlobalDefines.xml", and this is the file you want. Right click it and choose to open in Notepad (NOT Wordpad!).
3. It might look scary, but don't panic! First things first-- choose File->Save As, and back this file up in a place you'll know to look (such as My Documents).
4. Now to the single edit: press CTRL+F, which brings up the Find dialogue. Search for the following: BARBARIAN_MAX_XP_VALUE
Below this line in the code is a <Value> tag-- simply change the 30 to whatever number you deem to be reasonable.

60 would be three promotions, 100 would be four, 150 would be five, etc.
5. Once you've changed the 30 value to whatever number you wanted, save the file and you're finished!
Happy xp farming!
