Things run faster when I'm playing the game separate from construct..

Is there a way to optimize this so it'll run at the same speed for every computer?

If you are talking about making a game framerate independent you need to incorporate delta time into any movement that is not a native construct behaviour.

See this tutorial: construct.net/en/tutorials/delta-time-framerate-71

If you're talking about optimising for performance, you can't guarantee it will run the same on every device. Just optimise as best as possible. Can't give much more info without specific issues.