A call to `importlib.__import__()` normally locks the import for the module being worked on; this, however has a performance impact for modules that are already imported and fully initialized. An example of this are inline `__import__()` calls in a hot path that is called repeatedly during the life of the process.

Proposal: A two steps check in `importlib._bootstrap._find_and_load()` to avoid locking when the module has been already imported and it's ready.