This can be a concern only for scalpers who are after a few pips profit per trade and/or use scalping EAs.
My own broker has some slippage, but it sometimes goes in my favour, so I dont care.
I dont use EAs either.
There is simply one thing I d like to say. That your broker has some execution delay is no proof they re trying to rip you off.
You should know that there s no such thing as a mini lot or even a standard 100k lot in the interbank market. Those banks exchange 1 M lots. So your order must be " repackaged " in some way before it reaches the open market unless another retail trader happens to be available as your conterparty.
That is why demo accounts might perform better than live accounts even with " honest brokers ".
How Broker manipulate Metatrader using Plug-In
Your order on a demo account never needs repackaging and bundling with other retail orders.
There are brokers with instant execution, but they are often market makers who simply trade against YOU for a fraction of a second. They take your order instantly and they assume the risk of being your conterparty for the short time it takes for them to turn around, bundle the orders together and hedge their position on the open market ( those are the few " honest " market makers of course...a rare breed of course; most will do all that BEFORE they confirm your order) .
Finally, there is ping time that is the limited speed signals travel even with modern fiber optics added to the server s reaction time.
If you re in the USA and your broker is in Australia, you cant get anything better than 200-250 ms ping for the round trip: already one fifth of a second. You might want to check where is your broker s closest server located ( some brokers have servers in multiple locations ) because your EA sends queries to your broker that will be answered only after one round trip ( already giving you a slightly outdated quote ) and you need one half ping for the order to go back to the broker.