When you get different results with different brokers and don't know why, the quickest way to find out is looking in the performance report. There you can see which parameters come out very different.

IB is no good choice for retail Forex trading due to their high margin and capital requirement, and their complex cost structure. Since annual return is profit divided by required capital, you get of course a much smaller annual return with IB than with normal Forex brokers. The real difference is not as bad, since you normally have anyway more capital on the account than the required minimum. Still, I would not trade a Forex strategy with IB, at least not with small capital.