I am launching IronPython 2.7.3 on Windows 7 and it is taking more than 15 seconds. Why is it so slow? And how to fix it? The computer is a Samsung NP300E5A(Celeron B800,2gb) notebook.
There are a few reason why IronPython is slow to startup.
First, if you didn't use the installer (which will ngen the assemblies), the JIT compiler has to convert the IronPython assemblies from MSIL bytecode to native code, and that takes time, as it's a lot of code. So use the installer on manually ngen the assemblies.
Second, the actual Python code is also JIT compiled, although not right away to reduce the penalty; startup time used to be much worse when all Python code was JITted. The .NET JIT isn't fast enough for my liking.
Finally, it's not a powerhouse of a laptop. That said, even on my SSD-equipped quad core it still takes a few seconds to get started.
IronPython's startup time has improved a lot, to the point where it's now really hard to optimize further - profiling is hard (small sample size) and there's no obvious wins. It's "uniformly slow code" now, unfortunately.
IronPython's strength right now lies in long-running processes where the JIT can get some big wins, and not in short ones where it's more of a hindrance.
IronPython launching very slowly