Slippage in most cases is independent of mt4 itself. There are differences in quotes (if you want to copy signals form one broker to another)and also during some events liquidity provides change their quotes in very huge steps (price changes for example from 1.2 to 1.202 and there is nothing in between).There is nothing you can do about it.
You could lower latency of your trades execution if you would buy a server in the same place or company which your broker uses.However it would be costly and has nearly no meaning for retail trader. On this level it really makes no difference if you place your order 200 miliseconds earlier or later.
Of course virtual server has other adventages. It's working 24h a day for like 98% of the time which is a great thing ifyou use some EAs.