The Marco Show Software Performance: Avoiding Slow Code, Myths & Sane Approaches – Casey Muratori | The Marco Show
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Sep 17, 2025 
Casey Muratori, a programmer and performance advocate with a background in game development, joins for a compelling discussion on software performance issues. He delves into the frustrations surrounding slow software despite powerful hardware, sharing insights into the notorious Windows Terminal controversy. Casey emphasizes avoiding 'ridiculously slow' code and practical strategies for performance gains, such as parallel processing in Java. He also tackles the ethical implications of AI, advocating for respectful use of data in technology.
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Windows Terminal Performance Story
- Casey described discovering Windows Terminal was extremely slow when rendering many escape codes and engaging with the project maintainers.
- He then built a simple fast terminal renderer over a weekend to prove the performance problem and spur fixes.
File Format Determines Parallel Parseability
- File format dictates how easily you can parallelize parsing; simple line-based text is trivial to shard.
- Complex formats (JSON, compressed or nested binaries) make multi-threaded parsing much harder.
Use Per-Core Reduction Then Merge
- Partition input across cores and compute local min/max/average then merge results to scale linearly.
- Design algorithms around associative reductions to avoid cross-thread synchronization.