René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"General optimisations for dict lookup/insert performance","articleBody":"### Proposal:\n\nThere's room for tiny refactorings in the `Objects/dictobject.c` that may allow speedups, for example via better CPU cache behavior, compiler hints, cheap checks \u0026 fast exits for common cases. In my guess-timation, they may bring about upto 10% overall lookup/insert performance gains. That's more of an un-scientific intuition at best right now, but I'm laying some ideas out here:\n\n* `compare_unicode_unicode()`: can benefit from pointer-equality and branch prediction, and reducing unnecessary function calls\n\n* `compare_generic()`: can use early rejections on hash-mismatch, avoiding `RichCompareBool` calls\n\n* `unicodekeys_lookup_unicode()`: pointer-equality for the common case can precede `do_lookup` which today is invoked everytime for all cases\n\n* `find_empty_slot()`: early termination / separate path for first iteration can speed up insertions, especially for lightly-populated dicts\n\n* `build_indices_generic / build_indices_unicode ()`: breaking out the first-probe success case may speed up dict resize operations\n\nI welcome feedback on how to raise this proposal differently, but otherwise I'd like to work on these ideas and quantify them. I feel modern CPUs have deep pipelines and these optimizations may help us avoid some cache-thrashing. These changes are purely performance oriented and don't change functionality / API / ABI and should be thread-safe too.\n\n### Has this already been discussed elsewhere?\n\nThis is a minor feature, which does not need previous discussion elsewhere\n\n### Links to previous discussion of this feature:\n\n_No response_","author":{"url":"https://github.com/caje731","@type":"Person","name":"caje731"},"datePublished":"2026-02-24T14:04:16.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/145179/cpython/issues/145179"}