Production Tuning

PerfLocale is fast by default. These four settings are what take it from fast to imperceptible, in order of impact.

What to expect

Measured on the PerfLocale test harness - WordPress 6.9, PHP 8.4, MariaDB 10.6, 5 active languages, 200 translation groups, 1000 posts. Warm-cache second request. Query counts are deterministic and should reproduce closely on any stack; wall-clock timings depend on your hardware, hosting and other plugins, so they are deliberately not quoted here.

Query counts don’t scale with site size. Same numbers on a 15-post site and a 1000-post site - PerfLocale’s caches are bounded per request, not per total content.

Paginated archives get an extra optimization for free. On language-filtered front-end archive queries PerfLocale suppresses WordPress core’s deprecated SQL_CALC_FOUND_ROWS — which, combined with the language JOIN, forces MySQL to scan every matching row (ignoring LIMIT) just to count them — and supplies the pagination count from a generationally-cached COUNT instead. It’s on by default and needs no configuration; to restore core’s behaviour, add_filter( 'perflocale/query/optimize_found_rows', '__return_false' ).

1. Persistent object cache

The single biggest win. Turns ~100 queries per page into ~13. Every WordPress site benefits; multilingual sites benefit most because PerfLocale reads small data structures (language list, translation links, slug translations) on every request — all of those become free.

Redis (recommended)

# Install Redis + the PHP extension
sudo apt install php8.3-redis redis-server
sudo systemctl enable --now redis-server

# Install & activate the WordPress plugin
wp plugin install redis-cache --activate
wp redis enable

Verify:

wp eval 'echo wp_using_ext_object_cache() ? "YES" : "NO";'
# → YES

Alternatives

• Memcached - simpler, functionally equivalent for this workload. Install the Memcached drop-in.
• Object Cache Pro - commercial, tighter WooCommerce integration. Often bundled with managed hosts (Kinsta, Pressable, Cloudways).

2. PHP OPcache

Caches compiled PHP bytecode. Bundled with PHP 5.5+, almost always available, but defaults are too small for WordPress - hot files get evicted. Give it room:

# /etc/php/8.3/fpm/php.ini
opcache.enable=1
opcache.memory_consumption=256
opcache.max_accelerated_files=20000
opcache.interned_strings_buffer=32
opcache.validate_timestamps=0 ; production only - requires fpm reload on deploy
opcache.save_comments=1 ; required for WordPress

Verify:

wp eval 'print_r( opcache_get_status( false )["opcache_statistics"] );'
# Look for "opcache_hit_rate" — should be > 99% on a warm pool.

validate_timestamps=0 means OPcache won’t notice file edits. systemctl reload php-fpm after every deploy. Don’t set this on a dev machine.

3. CDN edge caching

The fastest request is the one PHP never sees. With a CDN in front, most visitors get HTML from the edge. PerfLocale ships two features that make edge caching work correctly on multilingual sites:

Cache-Tag headers

Enable at Settings → Advanced → CDN Cache-Tag Headers. PerfLocale emits a tag on every response:

Cache-Tag: perflocale,lang:fr_FR,lang-slug:fr,post:42,post-type:post

Your CDN (Cloudflare Enterprise, Bunny, Fastly, KeyCDN…) can then purge surgically - flush everything tagged lang:fr_FR, or just post:42, without nuking the whole cache. Full reference: Cache-Tag Headers.

Edge language detection

On Cloudflare Workers, Vercel Edge, or Netlify Edge, you can resolve the visitor’s language at the edge and include it in the cache key. Result: / caches separately per language, zero round-trips to WordPress for language detection. Full guide: Edge Integration.

One thing to avoid: Vary: Accept-Language. Shreds hit rate - every distinct browser Accept-Language header produces a separate cache entry. PerfLocale deliberately does not emit this header. Use URL-based routing (/de/, subdomain, or per-domain) or edge-hint headers instead.

4. String-translation mode

Under Settings → Performance, choose how UI string translations are stored:

For normal production servers, keep the default.

5. Deny web access to the export directory

Not a speed setting, but it belongs in the same pass. Exports land in wp-content/uploads/perflocale/exports/, which is inside the web root. PerfLocale writes a Deny from all .htaccess there, and nginx and Caddy ignore .htaccess, so on those servers you need a real rule:

location ~* /wp-content/uploads/perflocale/exports/ {
	deny all;
	return 404;
}

Tools → Site Health checks this for you by writing a temporary random file and requesting it over HTTP. If it comes back, you get a critical result with the snippet. See Security for the full explanation.

Measuring your own numbers

Drop this into wp-content/mu-plugins/perf-log.php for a tuning session. Remove it when done.

<?php
if ( ! defined( 'SAVEQUERIES' ) ) define( 'SAVEQUERIES', true );
add_action( 'shutdown', function () {
	global $wpdb;
	$total = 0;
	foreach ( $wpdb->queries ?? [] as $q ) $total += (float) ( $q[1] ?? 0 );
	file_put_contents(
		WP_CONTENT_DIR . '/perf.log',
		sprintf( "%-40s queries=%3d time=%6.2fms\n",
			$_SERVER['REQUEST_URI'] ?? '?',
			count( $wpdb->queries ?? [] ),
			$total * 1000 ),
		FILE_APPEND
	);
}, 9999 );

curl -s -o /dev/null https://example.com/
curl -s -o /dev/null https://example.com/de/
tail /wp-content/perf.log

Run each URL twice - the second run is the warm-cache number that matters. If your query counts are far above the table above, one of the four layers isn’t doing its job. Check them in order: object cache, OPcache, CDN.

Related

• CDN Cache-Tag Headers - per-language CDN purging
• Edge Integration - Cloudflare Workers / Vercel / Netlify
• Performance feature page - the architectural choices that make PerfLocale fast by default