No, the problem is the internet between you and your trades and MT's server, not how fast your computer can do things.
Let's take a big closeout for example, 100 trades. You have to select each trade, close it, wait for the response, then go to the next one, close it, wait for the response and so on. You can do maybe 2 a second. The 1/1000th you use to read a defunct function doesn't even begin to feature.
MT 5 supposedly has an asynchronous mode and only tracks single positions, which in theory solve the time issues, but certainly not to the extent where you need inline functions. And frankly very few brokers use it. There's no demand for it.
Oanda is a bit better, there you can use the API to send an apposing trade, so if you have say 100 trades of 1000 units each you'll send a single order to close 100*1000 and they will do it server side, at their best server speed, which is almost instant, but if it's over more than 1 pair they have a delay written into their closes. So then you're waiting 1 second anyway per pair and you're back to the point where 1/1000th delay doesn't matter.
So unless you're using an enterprise level language and you're plugging directly into the banks with co-hosted servers empty functions simply doesn't matter.
You basically need to be into HFT for it to matter, and that means you have to get out of someone else framework and write your own from scratch and you'll probably have to use the FIX protocol which will create a massive amount of work for you.