Testing
Optimizing PageSpeed without measuring is guesswork. This guide covers how to structure a test-driven approach to performance optimization: establish baselines, validate that changes actually improved things, and prevent regressions with CI integration. Why Testing Optimizations Matters Performance optimizations frequently backfire: * Adding lazy loading to the hero image (the LCP
Testing
GraphQL's flexibility is a double-edged sword. The same feature that lets clients fetch exactly what they need also lets an attacker craft a query that brings your server to its knees. The same resolver pattern that makes GraphQL elegant also creates N+1 query problems at scale.
Testing
Performance is a feature in games. A 60 FPS game feels completely different from the same game at 30 FPS. Players notice stutters, long load times, and frame drops — and they stop playing. Performance testing catches regressions before players experience them. This guide covers tools and techniques for profiling game
Testing
pytest-xdist lets you run tests across multiple CPUs — or even multiple machines — without changing a single test. A 10-minute suite can drop to 2-3 minutes with 4 workers. Here's how to set it up correctly, including the database isolation patterns that trip up most teams.
Testing
Vitest runs tests in parallel using worker processes. How those workers are created — and how isolated they are from each other — determines your test suite's speed, stability, and compatibility with native modules. Vitest offers three pool types: threads, forks, and vmThreads. Knowing which to use can cut your
Testing
A test suite that takes 15 minutes to run is a test suite developers avoid running. The fix isn't always parallelism — often it's finding the 5% of tests consuming 60% of the time and making them faster. Here's a systematic approach to profiling and
Swift
XCTest includes a built-in performance testing API that lets you measure how long a block of code takes and compare it against a stored baseline. When performance regresses, the test fails — giving you an early warning before slow code ships to users. The measure Block The simplest performance test
Swift
Instruments is Apple's performance analysis tool included with Xcode. It attaches to a running process — including your test target — and records CPU usage, memory allocations, and retain cycles. When tests run slowly or your app leaks memory during a test run, Instruments shows you exactly where the time
Testing
App performance isn't tested — it's measured. Android's Macrobenchmark library gives you a framework for measuring startup time, frame rendering, and custom interactions on real devices. Baseline Profiles use those measurements to pre-compile critical code paths, and Perfetto lets you trace exactly what'
ScyllaDB
ScyllaDB delivers Cassandra-compatible APIs with a rewritten Seastar-based engine that achieves dramatically higher throughput. Testing ScyllaDB applications requires validating both Cassandra compatibility and ScyllaDB-specific behaviors like shard-per-core data distribution. This guide covers both angles. ScyllaDB Testing Landscape ScyllaDB is a drop-in replacement for Cassandra
WebAssembly
WebAssembly performance is close to native — but "close" needs to be measured. Whether you're evaluating the overhead of crossing the WASM/JS boundary, comparing execution speed between runtimes, or profiling where your WASM module spends its time, you need specific tools: Criterion for Rust-level benchmarks,
CI/CD
A 45-minute test pipeline kills developer productivity. By the time CI finishes, context has switched, the fix is forgotten, and momentum is gone. Test parallelization is the highest-leverage optimization available — most teams can cut their pipeline time by 60-80% without changing a single test. This guide covers