# Performance Baselines

The same baseline-pinning pattern used for comparing weights (see [Comparison Editor](/docs/editors/comparison-editor)) applies to comparing performance: pin a known-good [runtime trace](/docs/profiling/runtime-traces) as the baseline, and compare a new trace against it, rather than trying to judge a single trace's numbers in isolation.

## Why a baseline matters more for performance than for weights

A weight diff has a natural zero point - unchanged is unchanged, regardless of context. A performance number rarely does: whether "340ms per step" is good or bad depends entirely on what it's being compared to. Pinning a baseline trace turns "is this fast" into the much more answerable "is this faster or slower than the last known-good run, and where specifically did the difference come from."

## What gets compared

With a baseline and a candidate trace both loaded, comparison is available at the same granularities as everywhere else in Tensormorph:

-   **Whole-run** - total wall-clock time, and where estimable, [FLOP](/docs/profiling/flops) throughput.
-   **Per-layer** - a [Layer Profile](/docs/editors/signal-and-distribution-editor) of per-layer timing, baseline against candidate, immediately showing which specific layer regressed rather than only that the total got slower.
-   **Per-step, over training** - for a captured sequence of steps rather than a single one, whether a regression is consistent or intermittent.

## Regression as a Problems-panel entry

A performance baseline comparison configured with a threshold (candidate slower than baseline by more than X%) can raise a flagged entry in the **Problems panel** the same way a statistical [outlier](/docs/inspect-and-analyze/outliers-and-anomalies) does - making a performance regression something [CI Validation](/docs/cli-and-automation/ci-validation) can gate on, not just something a human notices by eye.

## Related resources

-   [Runtime Traces](/docs/profiling/runtime-traces) - capturing the traces a performance baseline compares.
-   [FLOPs](/docs/profiling/flops) - a structural, estimate-based complement to a measured baseline comparison.
-   [CI Validation](/docs/cli-and-automation/ci-validation) - gating a pipeline on a performance regression.