Let's be honest here
The Construct has a great potential maker, a great proposal, it goes forward.
Now, I think that the construct should have more programmers around the world, do not see the Haiku.
The Construct is a maker that has a future is open-source, a great choice of maker, now to your points:
It is slow and different from others
It uses DirectX, or anything Linux or Mac, unlike other open-source programs.
Now I think what should be done about it:
Add a bunch of programmers to help you
Use SDL or Allegro sluggish than the game
Do what I said, will help a lot.