A complaint that I have is that the MT5 demo account does not show a negative (loss) value as soon as an order is open. I can open a position and it immediately shows $0 in the profit column. I should show -$6.25 with a 1 tick spread (bid & ask) for the EU6 as an example. This is not realistic like it would be in a live account and is very misleading. Do you want me to provide a video of what I am stating?
MT5 demo is local simulation (all order are executed locally on your computer - Nothing is actually being sent to the exchange). Once live, all orders will be sent to the exchange and will then be executed based off the exchange rules and live market conditions. Any performance reports being tracked using demo should be considered Hypothetical.