Response Time
Response time is the total time between a request being sent and the complete response being received — the end-to-end metric users actually experience, encompassing network latency, server processing time, and data transfer. It's the most commonly reported, and most commonly misreported, performance metric.
Reporting response time as a single average is the most common way this metric gets misused — see percentile latency for why the tail of the distribution, not the average, usually determines whether real users perceive a system as fast or slow.
Response time budgets are often broken down by layer for diagnosis: how much time is network latency, how much is server processing, how much is database query time, how much is client-side rendering — since "the response was slow" alone doesn't tell you which layer to actually go fix.
