Browser caching setup for 1C-Bitrix

You open a Bitrix site on a repeat visit—load time 4 seconds. Waterfall: 80 requests to static files, each returning 304 Not Modified. TTFB is 200 ms, but the browser still checks every file. The root cause is incorrect caching headers. Our team with over 5 years of Bitrix experience handles this turnkey.

Proper configuration eliminates unnecessary requests: browsers store files locally and don't contact the server until the cache expires. Clients get faster load times; servers see reduced load. For example, after configuration on one project, the number of static requests dropped from 80 to 12, and load time from 4 seconds to 1.2 seconds. Savings on hosting reached a significant monthly reduction due to lower server load.

What are Cache-Control and Expires?

Cache-Control is an HTTP header that tells the browser how long to cache a resource. The max-age parameter specifies the time in seconds. Expires is an older header still used in some cases. According to RFC 7234, Cache-Control takes priority over Expires. For static files with hashes, we use max-age=31536000 (1 year) with the immutable flag.

Freshness vs. Validation

Freshness gives zero load time from cache. Validation saves bandwidth but not RTT. For maximum performance, we configure both mechanisms.

How to configure nginx for browser caching in Bitrix?

server {
    # HTML — short cache with revalidation
    location ~* \.html?$ {
        add_header Cache-Control "no-cache, must-revalidate";
        etag on;
    }

    # CSS, JS with hashes in names (Vite/Webpack) — long cache
    location ~* /build/assets/.*\.[a-f0-9]{8,}\.(css|js)$ {
        add_header Cache-Control "public, max-age=31536000, immutable";
        access_log off;
    }

    # Static files without hashes — moderate cache
    location ~* \.(css|js)$ {
        add_header Cache-Control "public, max-age=604800";
        etag on;
    }

    # Images
    location ~* \.(jpg|jpeg|png|gif|webp|avif|ico|svg)$ {
        add_header Cache-Control "public, max-age=2592000";
        access_log off;
    }

    # Fonts
    location ~* \.(woff|woff2|ttf|otf|eot)$ {
        add_header Cache-Control "public, max-age=31536000, immutable";
        add_header Access-Control-Allow-Origin "*";
        access_log off;
    }

    # Bitrix resources (without hashes)
    location ~* ^/bitrix/(js|css|fonts)/ {
        add_header Cache-Control "public, max-age=604800";
        etag on;
    }
}

The immutable directive prevents the browser from re-checking the file even on forced refresh (Ctrl+F5). Only apply it to files with version hashes in the name—this is safe.

Why is resource versioning important?

Without versioning, a long cache is risky: update your CSS and users will see the old design for a week. The solution is a hash in the filename.

Bitrix's built-in mechanism uses the sessid parameter in the URL. It changes on every session, breaking the cache more often than needed. Better to use Vite/Webpack: app-B3vCf7Tf.js. For such files, set max-age=31536000, immutable.

If you don't use a bundler, add a version manually:

// In header.php of the template
$version = trim(file_get_contents($_SERVER['DOCUMENT_ROOT'] . '/version.txt'));
echo '<link rel="stylesheet" href="/css/custom.css?v=' . $version . '">';

The version.txt file is updated in CI/CD on every deployment.

How to configure Apache .htaccess?

<IfModule mod_expires.c>
    ExpiresActive On

    ExpiresByType text/html "access plus 0 seconds"
    ExpiresByType text/css "access plus 1 week"
    ExpiresByType application/javascript "access plus 1 week"
    ExpiresByType image/jpeg "access plus 1 month"
    ExpiresByType image/png "access plus 1 month"
    ExpiresByType image/webp "access plus 1 month"
    ExpiresByType font/woff2 "access plus 1 year"
</IfModule>

<IfModule mod_headers.c>
    <FilesMatch "\.(css|js)$">
        Header set Cache-Control "public, max-age=604800"
    </FilesMatch>
</IfModule>

What is included in the caching setup?

Total 7–14 hours. The cost of setup depends on the scope of work and server configuration—contact us for a quote. The result is faster load times and reduced server load.

How to verify the configuration?

curl -sI https://site.ru/css/styles.css | grep -i "cache-control\|expires\|etag"

Chrome DevTools → Network → select a resource → Headers: check Cache-Control in Response Headers, and see from cache / from disk cache in the Size column on repeat loads.

Case study

On an e-commerce site with a catalog of 50,000 products, after configuring browser caching:

• Page load time decreased from 4.2s to 1.8s (57% reduction).
• Server requests dropped from 95 to 22.
• CPU load fell by 40%, leading to significant monthly hosting savings.

After implementing resource versioning, the problem of outdated design disappeared completely. The client is satisfied.

Common mistakes in browser cache configuration

Frequent issues we resolve during Bitrix project audits:

• Too long max-age for HTML pages—users see stale content after updates. For HTML, use no-cache, must-revalidate.
• Missing versioning for CSS/JS—after deployment, the browser continues using old cache. Solution: hash in filename or ?v= parameter.
• Mixing Expires and Cache-Control headers—they conflict; Cache-Control takes priority, so remove Expires.
• Missing Vary: Accept-Encoding on compressed resources—CDN may serve compressed version to browsers without gzip support.
• immutable directive for files without hashes—browser won't fetch updates even on forced reload.

A proper caching strategy accounts for resource type, versioning scheme, and Bitrix platform specifics.

Evaluate your project—contact us for a free consultation. We guarantee results.

Related links: Wikipedia: HTTP cache, Wikipedia: ETag.

80% of Bitrix sites slow down due to one table

b_iblock_element_property is an EAV structure where each row stores one value of one property of one element. A catalog of 50,000 products with 30 properties yields 1.5 million rows. The smart filter performs a JOIN of this table with b_iblock_element on five properties, and MySQL performs a full table scan for 3–5 seconds. Our experience shows that without intervention in this table, site acceleration is impossible. We take on projects where load time has dropped to 8–10 seconds and bring TTFB back to <200 ms within 1–2 weeks. Site speed optimization begins with an audit of slow queries and ends with a comprehensive turnkey infrastructure overhaul.

Contact us for an audit — we will identify bottlenecks within 2 hours and propose a concrete plan.

How to achieve TTFB below 200 ms?

Server optimization is the first step. Nginx configuration goes beyond simple gzip. Specifically:

• gzip_comp_level 4-5 — higher is pointless, CPU consumes more than it saves bandwidth.
• brotli on with brotli_static on for precompressed files.
• HTTP/2 with http2_max_concurrent_streams 128.
• fastcgi_cache for PHP responses — caching at Nginx level, bypassing PHP-FPM entirely.
• worker_processes auto, worker_connections according to the number of simultaneous connections.

PHP-FPM tuning: choose between pm = dynamic and pm = static. Static mode works best for dedicated servers with predictable load because it avoids forking overhead. Dynamic saves RAM under low traffic. Calculate pm.max_children as (available RAM - RAM for MySQL/Redis) / average process consumption. For OPcache set memory_consumption=256, max_accelerated_files=20000, and validate_timestamps=0 in production (restart PHP-FPM on deploy).

MySQL/MariaDB: the main bottleneck is almost always the database. Enable slow_query_log with a threshold of 0.5 sec and analyze every query via EXPLAIN. Set innodb_buffer_pool_size to 70–80% of available RAM on a dedicated server. Create composite indexes for faceted search: (IBLOCK_ID, IBLOCK_PROPERTY_ID, VALUE) on b_iblock_element_property. Run OPTIMIZE TABLE b_iblock_element_property after mass operations.

How to configure three-level caching?

Managed component cache. Set TTL individually for each component. Catalog — 3600 sec, news feed — 300 sec, banners — 86400. The same TTL everywhere guarantees either outdated data or useless cache.

Composite cache. The bitrix:composite technology lets Nginx serve ready HTML from a file; PHP is not executed. Dynamic zones (cart, authorization) are loaded via AJAX request through CBitrixComponent::setFrameMode(true). TTFB drops below 50 ms. However, not all components are compatible; $APPLICATION->ShowPanel() and direct output via echo break the composite. We check every page through the panel 'Performance → Composite Site'. According to Bitrix official documentation on composite cache, this is the most effective caching method for high‑load projects.

Comparison: composite cache is 10–20 times faster than managed cache in time to first byte.

Memcached / Redis. Transfer cache from the file system: sessions go to Redis (session.save_handler = redis) — 10–50 times faster than files, plus cluster support. Component cache goes to Memcached via .settings.php: 'cache' => ['type' => 'memcache']. Also enable ORM query cache so identical GetList() calls don't hit MySQL on every request.

What is the fastest way to optimize Bitrix database?

Default MySQL settings are insufficient. Indexes — composite for faceted search, covering for frequent queries. MySQL responds from the index without accessing the data. Partial indexes (MariaDB) for filtering by ACTIVE = 'Y'. Audit unused indexes — each slows down INSERT/UPDATE.

Partitioning. For tables with millions of rows: b_stat_session, b_search_content_stem, and highload-blocks with history. Partition by date — a query for 'orders in a month' does not scan three years of data. Partitioning also solves the problem of concurrent queries during exchange with 1С via CommerceML.

Real case: a catalog of 200,000 products, 50 properties. Filtering by 10 properties took 12 seconds. After creating composite indexes on (IBLOCK_ID, IBLOCK_PROPERTY_ID, VALUE) and partitioning b_iblock_element_property by IBLOCK_ID, execution time dropped to 0.3 seconds. MySQL load decreased by 40 times.

Cleanup. Over a year or two, any database accumulates: outdated search index, expired records in b_cache_tag, history in b_iblock_element_prop_s*, logs in b_event_log taking gigabytes. We set up regular cleanup via agents.

Frontend and CDN

Images account for 60–80% of page weight. Convert to WebP via CFile::ResizeImageGet() with BX_RESIZE_IMAGE_PROPORTIONAL + conversion. Use srcset + sizes — never load a 3000px image into a 400px block. Add loading="lazy" for everything below the fold. AVIF offers another 20–30% savings vs WebP.

CSS/JS optimization: use the built-in Bitrix module to merge and minify via 'Settings → CSS/JS Optimization'. Apply PurgeCSS / UnCSS — in a typical Bitrix project, 60–70% of CSS is unused. Use defer / async for non‑critical JS and inline critical CSS in <head> for instant FCP.

Fonts: add <link rel="preload" as="font" crossorigin> for the main font. Set font-display: swap — text visible immediately. Subset via pyftsubset — keep only Cyrillic + Latin, file size reduces by 3–5 times.

CDN: Cloudflare, BunnyCDN, AWS CloudFront, or Russian providers (Selectel CDN, VK Cloud CDN). Serve static assets (CSS, JS, images, fonts) via CDN with Cache-Control: public, max-age=31536000, immutable for files with a hash. Use on‑the‑fly image optimization (imgproxy, Cloudflare Polish) without load on origin.

Why is load testing necessary?

Not synthetic benchmarks, but real scenarios: k6 / wrk to simulate routes — catalog → filtering → product card → cart → checkout. Measure RPS, response time (p50, p95, p99), error rate. Use Xdebug (callgrind) or Blackfire for PHP profiling to find bottlenecks. The test result gives an objective picture of where it actually slows down, not where it 'seems'. After optimization, run again to record improvements.

Results

What is included in the work?

1. Current performance audit — analysis of slow queries, PHP profiling, check of caching, CDN, server settings.
2. Server configuration — Nginx, PHP-FPM, MySQL, Redis/Memcached, OPcache.
3. Caching optimization — managed cache, composite site, TTL configuration, tagged caching.
4. Database work — index creation, partitioning, cleanup, EAV table reorganization.
5. Frontend — images (WebP/AVIF), CSS/JS (minification, deferred), fonts (preload, subsetting).
6. CDN — connection, caching rule setup.
7. Load testing — real user scenarios, metric report.
8. Documentation — description of all changes, recommendations for further maintenance.
9. Guarantee — support for 1 month after delivery, ensuring all optimizations are stable.

Monitoring

Without monitoring, everything degrades in six months. A new module, uncleared logs, a template change — and speed returns to original. Use web-vitals API for Real User Monitoring from actual visitors. Set up synthetic monitoring with Pingdom or UptimeRobot for regular checks from different locations. Configure alerts — TTFB > 500 ms or LCP > 3 sec triggers notification.

Timelines and cost

Cost is calculated individually after the audit. Get a consultation for your project — we will evaluate the current state and propose an acceleration plan with specific timelines and budget. We are a team with 12+ years of experience in Bitrix, having completed over 300 site speed optimization projects. Contact us to start the performance audit today.