When investors are selling, the exchange rate of the foreign currency tells them how many units of the quote currency they will get for one unit of the base currency. Traders make decisions to buy if they think that the value of the base currency might increase. In the example, traders would purchase the US dollar with the Euro if they expect the value of the US dollar to increase to $1.31. The change that takes place is how the investor makes a profit.
In particular I would like to make the system a lot faster, since it will allow parameter searches to be carried out in a reasonable time. While Python is a great tool, it's one drawback is that it is relatively slow when compared to C/C++. Hence I will be carrying out a lot of profiling to try and improve the execution speed of both the backtest and the performance calculations.