The main selling point of JS is that it's fast to write and execute. Unity has been used for quite a few major commercial titles across all platforms at this stage and you can use either JS or C# for all of your code, so I wouldn't worry about performance to be honest.
If you're writing a simple 2D game first, just a tarted-up version of SR2, then you don't have Unity or anything else to add overhead so it'll be even faster again.
If you're writing a simple 2D game first, just a tarted-up version of SR2, then you don't have Unity or anything else to add overhead so it'll be even faster again.
