you will find this interesting
The least ethical, most dangerous, and most difficult to execute, is arb that takes advantage of discrepancies inside the software trading platform. This was noticed in 2007 by some EA developers that had strategies that could effectively trade price discrepancies between MT4 server and MT4 terminal. In certain builds of MT4, MT4 would only update the terminal every X ticks (let’s use 10 as extreme example) – the terminal price was guaranteed, so an EA could hammer the MT4 server for requests for new prices, and in some cases, the server price was different than the terminal price, thus allowing for risk free arb. This was however not ‘real’ trading.