Performance and caching for websites #

This page is for website creators who want fast pages. Exponential caches at many levels; most of them are on by default. This page shows the layers, the levers in order of effect, and how to measure (10.12 Performance tuning).

Contents #

1. The layers
2. The levers, in order of effect
3. Measure
4. Templates that stay fast
5. Clearing caches in the right order

The layers #

The levers, in order of effect #

From the installation book:

1. Serve with Velocity and its response cache; persistent workers keep the application warm.
2. Keep the content view cache and the template block cache on ([ContentSettings] ViewCaching=enabled, [TemplateSettings] TemplateCache=enabled, both shipped). Warm the site after a full clear with php bin/php/warm.php --allow-root-user.
3. OPcache.
4. APCu for the response cache's memory tier and the shared query cache.
5. The SQL query cache (querycache.ini), measured on your site.
6. The database itself (Databases).

Leave the static cache off (StaticCache=disabled, the shipped value); the response cache gives visitors the same benefit without slowing down publishing.

Measure #

php bin/php/console exp:benchmark --save=var/benchmark/base.json --allow-root-user
# change something
php bin/php/console exp:benchmark --baseline=var/benchmark/base.json --threshold=15 --allow-root-user

It prints median, p90 and p99 per page. Compare runs on the same machine, back to back (Benchmarking). Measure also in the browser: image sizes, number of requests and layout shifts often matter more than server time.

Templates that stay fast #

• Fetch only what you show: limit, class_filter_array, load_data_map where offered.
• No fetch of a whole subtree in the pagelayout without a cache block.
• Cache blocks keyed by exactly what the output depends on.
• Images in the right alias size, with width, height and loading="lazy" (Images and image variations).
• Stylesheets and scripts through the packer (Stylesheets and scripts).

Clearing caches in the right order #

A page rendered by old code between a cache clear and a PHP reload is cached again. So: INI and template caches, then reload PHP and restart Velocity, and only then the content, template-block and response caches. Under Velocity exp:velocity deploy does this in order (The order after a code change).

Related pages #

• View cache and cache blocks
• Caches
• Profiling and performance
• Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.