You need to take account of the difference between Demo and Live MT4 accounts.

There is no slippage in Demo accounts.

This is because demo accounts do not replicate market conditions and all orders are executed at the exact price in the chart without any delays or slippage.

For example, your order which size is 10 lots(1,000,000 units) can also be executed when there is only market liquidity for 0.1 lot(10,000 units) in Demo accounts.

This is a common condition for all brokers’ MT4 Demo.

Both XM Live (up to 10 accounts per trader) and Demo (unlimited amount) accounts are available for free.

XM Official Website