... why do you choose Python to substitute for java , C++ or visual Basic ?
Developing an application is simply much faster. The code is easier to maintain by yourself and other people.
Like Java, Python has JIT compilers and speed optimized modules available for higher speed applications. For real speed critical applications you can easily include C or C++ in your Python code. This is common practice at Google, and might explain why Microsoft lacks behind.
In contrast to Visual Basic, Python is open source and works an many different operating systems. The Boa Constructor IDE is much like the Visual or Delphi RAD.
your are right! In the real world it is more important to be out on the market with a working program at the right time. There are a few cases, where it is critical to milk the speed of program execution for every microsecond.