Optimizing TTFB (Time to First Byte) for 1C-Bitrix
TTFB is the time from sending an HTTP request to receiving the first byte of response. It's pure server time: DNS, TCP connection, SSL handshake plus page generation time. Google PageSpeed considers good TTFB < 200 ms. Standard Bitrix site without optimization has 800 ms – 3 seconds.
What TTFB Consists of in Bitrix
Typical breakdown on a heavy site:
| Stage | Time | What Affects |
|---|---|---|
| DNS + TCP + SSL | 20–100 ms | Hosting, CDN, geolocation |
| PHP initialization + Bitrix | 50–150 ms | OPcache, autoload |
| Kernel load, modules, prologue | 30–100 ms | Number of modules, include in init.php |
| SQL queries to database | 100–2000 ms | Indexes, cache, query optimization |
| Component execution | 50–500 ms | Component cache, template complexity |
| PHP buffer, obfuscator | 10–50 ms | Output settings |
On most projects, 60–80% of TTFB is SQL queries. Start with them.
OPcache — Basic PHP Optimization
PHP without OPcache compiles every file on each request. Bitrix when fully loaded includes 200–500 PHP files. OPcache caches compiled bytecode:
[opcache]
opcache.enable = 1
opcache.memory_consumption = 256
opcache.interned_strings_buffer = 16
opcache.max_accelerated_files = 20000
opcache.validate_timestamps = 0 ; on production — don't check file changes
opcache.revalidate_freq = 0
opcache.fast_shutdown = 1
opcache.enable_cli = 0
validate_timestamps = 0 is critical for speed. OPcache then doesn't see file changes without reset. After deployment, clear cache: opcache_reset() or cachetool utility. Without this setting, OPcache does stat() for each file per request — hundreds of syscalls.
max_accelerated_files = 20000 — Bitrix with typical modules has 5000–15000 PHP files. If limit is smaller — some files aren't cached. Check: opcache_get_status()['opcache_statistics']['num_cached_scripts'].
Page and Component Cache
Most effective way to lower TTFB is not generate page at all, return cached HTML. Bitrix can cache at several levels:
Component cache ($cache_time in .parameters.php). Standard bitrix:catalog.section component is cached for one hour. With proper configuration, repeat request has 5–20 SQL queries instead of 100–300.
Managed cache / Composite. Composite Site technology in Bitrix divides page into cacheable and dynamic parts. Cacheable part (main column, menu, header) is served immediately, dynamic part (cart, notification count) loads via AJAX. With proper setup, main HTML TTFB drops to 50–100 ms.
Enable Composite: Settings → Performance → Composite Site. Components are marked as dynamic via CBitrixComponent::setDynamicMode() or bitrix:catalog.top.menu with DYNAMIC = Y parameter.
HTML cache nginx. Fastest option — nginx serves static HTML without running PHP. Implemented via nginx FastCGI cache or Varnish in front of Bitrix. Requires proper invalidation on content update.
Optimizing Prologue and init.php
Every Bitrix request executes /bitrix/php_interface/init.php. If heavy classes are loaded, SQL queries made, or third-party libraries included — this adds to every request.
Check /bitrix/php_interface/init.php:
- no
includeof files needed only in specific controllers - no initialization of third-party SDKs (1C integration, payment systems) on every request
- no SQL queries in
OnPageStartevent handlers
Lazy-loading via Loader::includeModule() — modules are included only where needed. Don't include entire module list in init.php globally.
Database: Connection and Queries
Time to establish MySQL connection is 1–5 ms for local connection. When database is on separate server — 5–20 ms for TCP connection. Persistent connections (MYSQL_PCONNECT) allow reusing connection between requests within PHP-FPM worker.
In /bitrix/php_interface/dbconn.php:
$DBPersistent = true; // enable persistent connections
Persistent connections reduce overhead but increase open connections on MySQL server. max_connections in my.cnf must be greater than PHP-FPM workers × virtual hosts.
Measuring TTFB by Stage
Diagnostics tool — Bitrix performance panel (/bitrix/admin/perfmon_panel.php or icon in bottom right). Enable profiling and open page. Panel shows:
- total execution time
- SQL query time cumulative and per query
- component execution time
- cache file operations count
For external measurement — curl -o /dev/null -s -w "Time to first byte: %{time_starttransfer}s\n" https://yoursite.ru/. Make 3–5 measurements: first may be with cold cache.
Optimization Timeline
| Task | Time | TTFB Reduction |
|---|---|---|
| OPcache configuration | 0.5 day | 100–300 ms |
| SQL optimization (indexes, cache) | 3–5 days | 200–1500 ms |
| Component cache tuning | 1–2 days | 100–500 ms |
| Enable Composite Site | 2–3 days | 300–800 ms |
| Switch to Redis cache | 1 day | 20–100 ms |
| Nginx FastCGI cache | 2–3 days | 200–600 ms |
Realistic goal for e-commerce on Bitrix with comprehensive optimization: TTFB < 300 ms for cached pages, < 800 ms for dynamic (personal account, checkout).