why does python take a long time to start up?

Python's startup time can be influenced by several factors, similar to the issues discussed in various WWDC sessions about app performance and launch times. Here are some relevant points from the context provided:

1. Initialization of Global Variables:

   • In languages like C and Objective-C, global variables are initialized at startup, which can significantly slow down the launch time. Swift avoids this by using lazy initialization, which initializes variables on first use (Migrate your app to Swift 6).

2. CPU Usage and Execution Time:

   • High CPU usage and long execution times during the initial launch can cause delays. Tools like the Time Profiler in Xcode can help diagnose these issues by visualizing CPU usage and identifying long hangs during startup (What’s new in Xcode 16).

3. Loading Assets and Parallelization:

   • Loading assets serially on the main thread can cause significant delays. Parallelizing the loading process and moving execution to the background can improve startup times (What’s new in Xcode 16).

4. Build and Debugging Processes:

   • Implicit steps in the build process, such as building binary versions of modules, can lead to slowdowns. Making these steps explicit and enabling parallel builds can result in more predictable and faster builds (What’s new in Swift).

5. Performance Tools:

   • Using performance tools like Instruments in Xcode can help identify and address performance bottlenecks, including slow app launches and excessive disk writes (What’s new in Xcode 16).

In summary, Python's startup time can be affected by similar factors such as initialization of global variables, CPU usage, asset loading, and build processes. Using appropriate tools to diagnose and optimize these aspects can help improve startup performance.