Performance
Virus scanning
Virus scanners are an essential component of system protection, but the performance impact can be severe for applications like Hugo that frequently read and write to disk. For example, with Microsoft Defender Antivirus, build times for some sites may increase by 400% or more.
Before building a site, your virus scanner has already evaluated the files in your project directory. Scanning them again while building the site is superfluous. To improve performance, add Hugo’s executable to your virus scanner’s process exclusion list.
For example, with Microsoft Defender Antivirus:
Start > Settings > Privacy & security > Windows Security > Open Windows Security > Virus & threat protection > Manage settings > Add or remove exclusions > Add an exclusion > Process
Then type hugo.exe and press the Add button.
Virus scanning exclusions are common, but use caution when changing these settings. See the Microsoft Defender Antivirus documentation for details.
Other virus scanners have similar exclusion mechanisms. See their respective documentation.
Template metrics
Hugo is fast, but inefficient templates impede performance. Enable template metrics to determine which templates take the most time, and to identify caching opportunities:
hugo build --templateMetrics --templateMetricsHintsThe result will look something like this:
Details
Template Metrics:
cumulative average maximum cache percent cached total
duration duration duration potential cached count count template
---------- -------- -------- --------- ------- ------ ----- --------
14.95 s 20.54 ms 278.74 ms 0 0 0 728 single.html
3.20 s 4.03 ms 33.23 ms 99 0 0 793 _partials/layouts/header/header.html
2.91 s 3.67 ms 29.58 ms 34 0 0 793 _partials/layouts/head/head.html
1.82 s 2.30 ms 23.97 ms 100 0 0 793 _partials/layouts/head/head-js.html
1.54 s 231.79 µs 23.49 ms 0 0 0 6632 _markup/render-link.html
1.37 s 1.73 ms 19.99 ms 91 0 0 793 _partials/layouts/header/qr.html
898.03 ms 338.24 µs 28.84 ms 0 0 0 2655 _markup/render-codeblock.html
828.14 ms 13.15 ms 42.49 ms 0 0 0 63 list.html
648.23 ms 817.44 µs 18.71 ms 100 0 0 793 _partials/layouts/footer.html
624.87 ms 787.98 µs 18.88 ms 23 0 0 793 _partials/opengraph/opengraph.html
515.61 ms 1.44 ms 23.17 ms 0 0 0 359 _shortcodes/code-toggle.html
431.74 ms 544.44 µs 16.66 ms 100 0 0 793 _partials/layouts/search/input.html
361.07 ms 227.66 µs 3.56 ms 58 0 0 1586 _partials/_inline/qr
353.60 ms 445.90 µs 17.17 ms 18 0 0 793 _partials/schema.html
292.99 ms 369.00 µs 18.63 ms 99 0 0 794 _partials/layouts/home/sponsors.html
282.03 ms 355.64 µs 15.65 ms 28 0 0 793 _partials/twitter_cards.html
279.74 ms 279.74 ms 279.74 ms 100 0 0 1 _partials/helpers/linkcss.html
230.48 ms 642.01 µs 9.04 ms 0 0 0 359 _markup/render-blockquote.html
227.22 ms 287.25 µs 12.19 ms 38 0 0 791 _partials/layouts/docsheader.html
206.41 ms 260.29 µs 10.04 ms 100 0 0 793 _partials/layouts/header/mobilemenu.html
202.75 ms 127.83 µs 15.57 ms 75 0 0 1586 _partials/helpers/linkjs.html
152.33 ms 192.09 µs 16.63 ms 100 0 0 793 _partials/layouts/search/results.html
137.02 ms 172.78 µs 10.88 ms 100 0 0 793 _partials/layouts/header/githubstars.html
121.06 ms 152.66 µs 1.55 ms 0 0 0 793 _partials/opengraph/get-featured-image.html
120.00 ms 165.07 µs 2.71 ms 15 0 0 727 _partials/layouts/in-this-section.html
116.10 ms 607.86 µs 11.93 ms 0 0 0 191 _shortcodes/new-in.html
84.77 ms 29.47 µs 5.92 ms 100 0 0 2876 _partials/inline/h-rh-l/validate-fragment.html
71.97 ms 80.51 µs 2.81 ms 0 0 0 894 _partials/inline/h-rh-l/get-glossary-link-attributes.html
70.27 ms 88.84 µs 5.66 ms 42 0 0 791 _partials/layouts/breadcrumbs.html
53.72 ms 1.68 ms 8.50 ms 0 0 0 32 _shortcodes/img.html
50.23 ms 63.34 µs 4.77 ms 0 0 0 793 _partials/layouts/hooks/body-main-start.html
48.01 ms 48.01 ms 48.01 ms 0 0 0 1 home.html
42.23 ms 42.23 ms 42.23 ms 0 0 0 1 404.html
41.13 ms 56.50 µs 2.49 ms 5 0 0 728 _partials/layouts/toc.html
39.26 ms 24.75 µs 1.28 ms 99 0 0 1586 _partials/_funcs/get-page-images.html
24.70 ms 31.15 µs 1.09 ms 100 0 0 793 _partials/helpers/gtag.html
23.87 ms 2.39 ms 10.01 ms 0 0 0 10 _markup/render-codeblock-goat.html
22.62 ms 96.24 µs 2.12 ms 80 0 0 235 _partials/layouts/blocks/feature-state.html
21.58 ms 9.07 µs 3.63 ms 100 100 2378 2380 _partials/helpers/funcs/get-github-info.html
21.19 ms 29.10 µs 902.28 µs 97 0 0 728 _partials/layouts/page-edit.html
20.03 ms 90.24 µs 1.49 ms 0 0 0 222 _shortcodes/include.html
20.02 ms 27.50 µs 593.31 µs 97 0 0 728 _partials/layouts/related.html
19.91 ms 19.91 ms 19.91 ms 0 0 0 1 /news/_content.gotmpl
19.83 ms 450.58 µs 4.69 ms 0 0 0 44 _shortcodes/deprecated-in.html
18.70 ms 18.70 ms 18.70 ms 100 0 0 1 _partials/helpers/funcs/get-remote-data.html
17.03 ms 74.37 µs 1.80 ms 0 0 0 229 _markup/render-table.html
10.61 ms 13.38 µs 2.29 ms 90 0 0 793 _partials/layouts/blocks/modal.html
10.14 ms 12.79 µs 1.17 ms 100 0 0 793 _partials/layouts/header/mastodon.html
9.57 ms 9.57 ms 9.57 ms 0 0 0 1 sitemap.xml
9.35 ms 24.68 µs 637.73 µs 50 0 0 379 _partials/layouts/blocks/alert.html
6.96 ms 8.77 µs 935.10 µs 99 0 0 794 _partials/layouts/search/button.html
5.38 ms 2.69 ms 3.20 ms 0 0 0 2 _shortcodes/quick-reference.html
5.32 ms 9.92 µs 1.03 ms 75 0 0 536 _partials/docs/functions-signatures.html
5.13 ms 6.47 µs 1.36 ms 100 0 0 793 _partials/layouts/hooks/body-end.html
5.02 ms 152.09 µs 1.22 ms 0 0 0 33 _shortcodes/glossary-term.html
4.65 ms 132.78 µs 1.71 ms 2 0 0 35 _partials/inline/get-resource.html
3.98 ms 1.99 ms 3.56 ms 0 0 0 2 _shortcodes/datatable.html
3.89 ms 388.92 µs 929.41 µs 0 0 0 10 _shortcodes/render-list-of-pages-in-section.html
3.80 ms 2.39 µs 963.41 µs 100 0 0 1586 _partials/layouts/header/theme.html
3.44 ms 6.42 µs 795.02 µs 19 0 0 536 _partials/docs/functions-aliases.html
3.10 ms 3.10 ms 3.10 ms 0 0 0 1 _shortcodes/glossary.html
2.57 ms 4.80 µs 256.63 µs 88 0 0 536 _partials/docs/functions-return-type.html
2.54 ms 2.54 ms 2.54 ms 100 0 0 1 _partials/layouts/home/opensource.html
1.97 ms 2.48 µs 501.94 µs 100 0 0 793 _partials/layouts/icons.html
1.85 ms 32.98 µs 178.18 µs 0 0 0 56 _shortcodes/eturl.html
1.74 ms 1.74 ms 1.74 ms 0 0 0 1 home.redir
1.70 ms 340.42 µs 596.87 µs 0 0 0 5 _shortcodes/qr.html
1.65 ms 235.82 µs 1.03 ms 0 0 0 7 _markup/render-passthrough.html
1.53 ms 1.53 ms 1.53 ms 0 0 0 1 _shortcodes/syntax-highlighting-styles.html
1.51 ms 1.51 ms 1.51 ms 0 0 0 1 _shortcodes/root-configuration-keys.html
1.45 ms 1.82 µs 839.08 µs 100 0 0 793 _partials/layouts/templates.html
1.34 ms 1.34 ms 1.34 ms 100 0 0 1 _partials/helpers/validation/validate-keywords.html
1.30 ms 1.30 ms 1.30 ms 0 0 0 1 _shortcodes/per-lang-config-keys.html
1.18 ms 21.89 µs 76.24 µs 0 0 0 54 _markup/render-image.html
1.15 ms 1.46 µs 36.50 µs 100 0 0 793 _partials/layouts/search/algolialogo.html
775.57 µs 775.57 µs 775.57 µs 100 0 0 1 _partials/helpers/picture.html
748.41 µs 374.21 µs 402.25 µs 0 0 0 2 list.rss.xml
718.91 µs 718.91 µs 718.91 µs 0 0 0 1 _shortcodes/figure.html
696.14 µs 232.04 µs 263.44 µs 0 0 0 3 _shortcodes/newtemplatesystem.html
676.21 µs 852.00 ns 16.23 µs 100 0 0 793 _partials/layouts/head/speculationrules.html
618.07 µs 618.07 µs 618.07 µs 0 0 0 1 _shortcodes/chroma-lexers.html
605.82 µs 763.00 ns 29.52 µs 100 0 0 793 _partials/layouts/hooks/body-start.html
444.33 µs 222.17 µs 342.78 µs 0 0 0 2 _shortcodes/highlight.html
398.33 µs 398.33 µs 398.33 µs 0 0 0 1 _shortcodes/render-table-of-pages-in-section.html
243.64 µs 121.82 µs 125.32 µs 0 0 0 2 _shortcodes/youtube.html
235.46 µs 39.24 µs 66.03 µs 0 0 0 6 _shortcodes/current-go-version.html
229.98 µs 12.78 µs 39.15 µs 0 0 0 18 _shortcodes/get-page-desc.html
193.19 µs 8.05 µs 34.85 µs 52 0 0 24 _partials/layouts/date.html
184.80 µs 184.80 µs 184.80 µs 0 0 0 1 _shortcodes/x.html
125.61 µs 125.61 µs 125.61 µs 0 0 0 1 _shortcodes/details.html
106.29 µs 106.29 µs 106.29 µs 0 0 0 1 _shortcodes/hl.html
81.00 µs 81.00 µs 81.00 µs 0 0 0 1 _shortcodes/syntax-highlighting-styles-light-with-counterpart.html
47.32 µs 23.66 µs 40.66 µs 0 0 0 2 _shortcodes/param.html
42.67 µs 42.67 µs 42.67 µs 100 0 0 1 _partials/layouts/home/features.html
37.00 µs 37.00 µs 37.00 µs 0 0 0 1 _shortcodes/instagram.html
35.17 µs 35.17 µs 35.17 µs 0 0 0 1 _shortcodes/vimeo.html
1.95 µs 1.95 µs 1.95 µs 0 0 0 1 home.headers
1.81 µs 258.00 ns 977.00 ns 0 0 0 7 _shortcodes/module-mounts-note.htmlFrom left to right, the columns represent:
- cumulative duration
- The cumulative time spent executing the template.
- average duration
- The average time spent executing the template.
- maximum duration
- The maximum time spent executing the template.
- cache potential
- Displayed as a percentage, any partial template with a 100% cache potential should be called with the
partialCachedfunction instead of thepartialfunction. See the caching section below.A 100% cache potential is calculated by comparing each execution’s rendered output to the first execution’s output, so it cannot detect side effects such as calls to
warnforerrorf, or execution order dependencies such as a conditional based onIsHome. A partial template that produces no visible output but performs validation, logging, or conditional logic based on context can show 100% cache potential even though caching it would suppress that behavior for all but the first invocation. Review the template’s logic before switching it topartialCached. - percent cached
- The number of times the rendered templated was cached divided by the number of times the template was executed.
- cached count
- The number of times the rendered templated was cached.
- total count
- The number of times the template was executed.
- template
- The path to the template, relative to the
layoutsdirectory.
Hugo builds pages in parallel where multiple pages are generated simultaneously. Because of this parallelism, the sum of “cumulative duration” values is usually greater than the actual time it takes to build a site.
Caching
Some partial templates such as sidebars or menus are executed many times during a site build. Depending on the content within the partial template and the desired output, the template may benefit from caching to reduce the number of executions. The partialCached function provides caching capabilities for partial templates.
Note that you can create cached variants of each partial template by passing additional arguments to partialCached beyond the initial context. See the partialCached documentation for more details.
Timers
Use the debug.Timer function to determine execution time for a block of code, useful for finding performance bottlenecks in templates.