November 1, 2025
Speed wars meet wiki feels
Sufficiently Smart Compiler
Java vs C speed war ignites: 'smart compilers,' 'buy GPUs,' and big nostalgia
TLDR: A classic debate flared: can super-smart compilers make high-level languages as fast as C, with Java’s runtime tricks cited as proof. Commenters split between data-driven believers and skeptics citing real‑world slowdowns, while one joked to “buy GPUs” and another reminisced about the old C2 wiki—tech drama meets nostalgia.
Can a “sufficiently smart compiler” make fancy high-level code run as fast as bare‑metal C? The old fight just reignited, with one camp pointing to Java’s rise from “sluggish” to “sometimes speedy” thanks to just‑in‑time tricks that learn at runtime, and studies and benchmarks. The skeptics clap back: those tests are tiny, real apps juggle tons of objects, and Java pays a cache penalty for all that abstraction.
Drama alert: purists ask when “C” stops being C if new rules let its compilers go turbo — is that performance or just rule‑bending? Others argue many optimizations are impossibly hard in theory but work fine in practice, so don’t dismiss them.
Meanwhile, the comments turned into a roast. gdiamos deadpanned that the smartest compiler is a human — “and slow.” The punchline escalates: “Build faster GPUs,” then “The more you buy the more you save,” and finally “find ways to keep errors shrinking.” Translation: throw hardware and math at it, kids. zkmon swerved into nostalgia, cheering the minimalist vibes of the ancient C2 wiki and its new popup navigation, plus a shoutout to Slashdot. The vibe: equal parts speed nerd brawl, budget memes, and old‑internet feels.
Key Points
- •The “Sufficiently Smart Compiler” argument claims high-level languages can match or exceed low-level language performance if compilers exploit high-level information.
- •Stalin for Scheme is cited as a real example of aggressive optimization, though not suited for large production programs.
- •Java’s performance improved through JIT optimizers leveraging runtime profiles and reference usage to optimize code and garbage collection.
- •Critiques note benchmarks often show Java slower than C on computational tasks and suggest Java’s object system can be cache-inefficient in larger applications.
- •C’s evolution (e.g., C99 aliasing rules) and optimized compilers enable aggressive optimizations; many compiler techniques are NP-complete or undecidable in general but still useful.