TagBenchmarking

TL;DR: Once a benchmark shows a win, put the optimized code back into the profiling harness. Compare the before and after memory and CPU profiles to see whether the larger execution path benefits too. A good benchmark table feels great. The before number is slower, the after number is faster, allocations drop, and the ratio looks impressive. After hours of staring at profiler stacks and benchmark output, that table feels like the finish line. Unfortunately, the table only describes the isolated...

TL;DR: Useful benchmarks are controlled experiments. Copy the relevant production code, trim away unrelated work, choose realistic parameters, measure one responsibility, and use short runs for direction before spending time on full runs. Most benchmark examples look cleaner than the code we work with. Suspiciously cleaner. They compare string concatenation with StringBuilder. They call a static method. They pass one value in and return one value out. Those examples are useful for learning...

TL;DR: Profilers show cost, not priority. Start with memory, then CPU, use filters to zoom into the code path you own, and let domain context decide which hot spots deserve a benchmark. The first profile is usually disappointing. You attach the profiler, run the profiling harness, take a snapshot, and get a giant list of allocations, call stacks, framework methods, runtime methods, transport code, serializer code, and your own code hiding somewhere in the middle. The tool did its job. It showed...

TL;DR: Before writing a benchmark, build a small profiling harness that makes the code path visible. Run it in Release mode, keep unrelated work out, add clear profiler snapshot points, and collect both memory and CPU evidence. Production code is a terrible place to start a performance investigation. There is too much happening at once. Production code is not bad; it is alive. It has real configuration and input/output, plus logging, retries, dependency injection, serialization, network calls...

TL;DR: A benchmark can tell you whether code got faster. It cannot tell you whether the code mattered. For that, use a loop: profile with a profiling harness, improve a hot path, benchmark and compare, profile again, then ship and observe production. The first benchmark I wrote looked deceptively easy. I needed a class, a few attributes, and a method. Then I could run BenchmarkDotNet and get a table. It looked a lot like unit testing, which made me dangerously confident. That confidence did not...