The volatility in the market may create conditions where Stop and Limit orders are difficult to execute, since the price might be many pips away due to the extreme market movement. Although the trader is looking to execute at a certain price, the market may have moved significantly and the order would be filled at the next best price or the fair market value. Similarly, increased trading volume may also result in slippage if sufficient liquidity does not exist to execute all trades at the requested rate.
Once a stop limit or stop loss order is triggered, it becomes a market order, and there is no guarantee it will be filled at any particular given price. Therefore, stop orders may incur slippage depending on market conditions.