# Performance notes

## The `?seo=` article filter

`GET /v1/article/` assesses the SEO status of articles in memory, because the status depends on the body, the site template and the authors. Every request assesses every visible article once, to fill `counts.suggestions`, and `?seo=` reuses that assessment to filter before paging. The cost therefore grows with the number of articles, not with the page size.

`TestSeoFilterPerformance` in `test/seo_filter_performance_test.go` (skipped with `-short`) measures 5,000 articles of about 5 KB each in one site on a temporary SQLite file, every article with suggestions, slowest of 3 runs:

| Request | Time |
| --- | --- |
| `?seo=suggestions&size=25` | 315 to 338 ms |
| default page, no `?seo=` | 307 to 329 ms |

The target is 300 ms for 5,000 articles. Both requests sit slightly above it on the development machine, so the test logs the target but only fails above 500 ms; no cache or index was added. Re-run it with `go test -tags nofrontend ./test/... -run TestSeoFilterPerformance -v -count=1` after a change to the assessment rules or the article repository.