Performance Testing · SRE · AI Performance
Make systems fast,
reliable, and observable.
The free, in-depth resource for performance engineers — complete tool tutorials, interactive calculators, a live site-speed analyser, and deep guides on SRE and the performance of modern AI systems.
Tutorials
Master every load testing tool
Ordered, hands-on courses — from your first script to distributed testing, correlation, and CI/CD.
Apache JMeter
The complete JMeter course: from installation to distributed testing, correlation, CI/CD, and reading results correctly.
21 lessons · Beginner → AdvancedOpenText LoadRunner
VuGen, Controller and Analysis end to end: recording, correlation, scenario design, rendezvous, and root-cause analysis.
12 lessons · Beginner → AdvancedGrafana k6
Modern code-first load testing in JavaScript: scenarios, executors, thresholds, CI integration, and xk6 extensions.
5 lessons · Beginner → IntermediateGatling
Scala/Java DSL load testing: simulations, injection profiles, assertions, and reading Gatling's reports.
3 lessons · IntermediateLocust
Python-based load testing: writing locustfiles, the live web UI, and scaling out with distributed workers.
2 lessons · Beginner → IntermediateTricentis NeoLoad
Enterprise performance testing with NeoLoad: Design Studio, populations, automatic correlation, and CI-first workflows.
1 lessons · IntermediateTools
Calculators & analysers
Instant, client-side performance utilities — plus a live site-speed analyser that recommends fixes.
Site Speed Check
Enter any URL — measure TTFB, payload, compression and caching, and get prioritised recommendations.
Analyse a site → Performance TestingSite Speed Check
Analyse any URL for TTFB, payload, compression and caching — with fixes.
Performance TestingPacing Calculator
Find the pacing / think time to hit a target throughput with N virtual users.
AI PerformanceLLM Cost & Latency Estimator
Estimate per-request and monthly token cost plus end-to-end latency for an LLM workload.
ConceptsLittle's Law Calculator
Solve for concurrency, throughput, or latency given the other two (L = λW).
SREError Budget Calculator
Turn an SLO target into allowed downtime and a burn-rate readout.
Articles
Go deep by topic
Performance Testing
Load & stress testing with JMeter, k6, Gatling, LoadRunner and NeoLoad.
SRE
SLIs, SLOs, error budgets, capacity planning, incident response, chaos.
AI Performance
LLM latency & throughput, token economics, GPU serving, RAG and vector-DB perf.
Observability
OpenTelemetry, Prometheus, Grafana, Datadog, Dynatrace, New Relic.
Concepts
Little's Law, queueing theory, percentiles, USL, GC tuning.
Fresh
Latest articles
Measuring LLM Inference Performance: Latency, Throughput, and Cost
The metrics that actually matter for LLM serving — TTFT, TPOT, tokens/sec, and cost per request — how they trade off, and how to load-test an inference endpoint.
Read →SLOs and Error Budgets: A Practical Guide for Performance Engineers
How to turn vague reliability goals into measurable SLIs, SLOs, and error budgets — and how that math directly governs release velocity and on-call load.
Read →Chaos Engineering: Testing Reliability by Breaking Things on Purpose
What chaos engineering is, how to run a safe first experiment, and how it connects to error budgets and SLOs.
Read →