Merging this PR will not alter performance

✅ 345 untouched benchmarks
⏩ 2 skipped benchmarks¹

_{Comparing hugovk:lazy-imports (120360c) with main (be48bcb)}

I think the

ElementTree: ModuleType | None
try:
    from defusedxml import ElementTree
except ImportError:
    ElementTree = None

import should also belong in getxmp()? It'd become a neat try: import; except: warnings.warn() early return too.

Thanks, a couple extra "icicles" knocked off.

With 3.15, on a different machine compared to yesterday:

main: 26 ms	PR before: 20 ms	PR after: 17 ms

It's certainly a bigger and unrelated change, but looks like Pillow only uses logging for a couple debug calls here and there in PIL.Image -- could be worth it to just get rid of it there (though real-world apps will generally probably import logging somehow either way, so additional laziness would need to be put in there in the stdlib...).

I made the olefile import eager again: it's an optional dependency and lazy imports affect how its related plugins get registered.

I'll have a look at logging.

Unfortunately it's not straightforward to lazy import traceback in the stdib, because if we get an exception during shutdown, the import machinery might already be shutdown: python/cpython#150073.

lazy import re in logging might be more doable, but in any case won't show up until Python 3.16.

Something like this?

--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
-import logging
...
-logger = logging.getLogger(__name__)
+class _LazyLogger:
+    """
+    Defer importing `logging` until the logger is first used to avoid slow import.
+    """
+
+    def __getattr__(self, attr: str) -> Any:
+        import logging
+
+        logger = logging.getLogger(__name__)
+        globals()["logger"] = logger
+        return getattr(logger, attr)
+
+
+logger = _LazyLogger()

Before: 16 ms	After: 12 ms

@hugovk That'd work -- but I'm also thinking... do we need the 4 logger.debug()s for importing plugin modules in PIL/Image.py at all?