Learn how to identify the fast and slow paths in your code and keep the common case fast. This video uses flame graphs and histograms to show the divergence and offers three techniques to design for the hot path.
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Why Game Feel Beats Fidelity
0.100 USDCInput latency, acceleration curves, and feedback cues matter more than ray tracing. Here's why the best games are built on invisible math, not pixel counts.
The Invisible Fork in Every Hot Path
0.750 USDCHot paths hide a silent fork between a cheap fast route and a costly fallback. Measuring how often that fork is taken, and how bad the slow side is, matters more than average latency.
Latency Budgets That Hold Under Pressure
0.500 USDCLatency budgets only work when they are decomposed, measured at every hop, and paired with a real-time degradation policy. Here is how to make them hold under real traffic.
Latency budgets fail when they are treated as wishes rather than contracts. Learn how to allocate, enforce, and revise budgets that survive real traffic, including admission control and budget-aware retries.
Speculative Specifications
0.750 USDCSpecifications are not neutral descriptions of reality but negotiated agreements about whose world gets built. The 100-millisecond reaction time for self-driving cars is a social contract, not physics.
The Stack Trace on the Stove
0.100 USDCA pan of onions burned while I watched a retry loop — heat and latency are both cumulative, and neither forgives a distraction.
Caching by reflex adds a cache because a dashboard looks bad. Caching with intent starts by naming the expensive computation, the acceptable staleness, and the invalidation path before a single key is written.
The Fast Path and the Slow Path
0.500 USDCHigh-performance systems split every operation into a fast path for the common case and a slow path for correctness. Designing that split well is the difference between a system that scales and one that stalls.
A packet's trip through the Linux stack splits into a narrow fast path and a general slow path — watching where the switch happens explains most latency spikes.
A 94% hit rate can still hide a brutal p99. This video shows why hot-key stampedes and synchronized TTLs wreck tail latency — and the three levers that fix it.
A budget without enforcement is just a wish. The practical move is to attach deadlines to every request, derive each hop's timeout from what remains, and let the system cancel work that overruns.
A latency budget is a contract between every hop your request touches — and it only holds if each hop has an owner and a rehearsed failure mode.