Performance

For the latest measured numbers from main, see Latest Benchmarks. This page covers what we measure and why phpdftk is fast at it.

All benchmarks run via PHPBench on the same machine, with no opcache and no Xdebug. phpdftk generates spec-compliant PDFs with proper xref tables, binary comments, and typed trailers — every measurement is on a real, valid PDF.

What’s being measured

• Generation — create N pages with text content and serialize to PDF bytes. Exercises the writer end to end (page tree, content streams, font registration, xref emission).
• Peak memory — memory_get_peak_usage(true) during generation. Captures the writer’s resident object graph.
• Parsing — open a PDF, extract catalog + info + version, iterate every page. Exercises xref resolution, dictionary parsing, and stream decoding.
• Reader compatibility — the same parsing benchmark run against PDFs that use spec-compliant xref tables and cross-reference streams. Some competitors fail outright on one or both formats.

Conformance validation overhead

Running ISO conformance validation during PDF generation (10 pages, embedded TrueType font) adds roughly 25–35 ms for most profiles. PDF/R-1 is an outlier on the cheap end at roughly 4 ms, because it doesn’t require font embedding.

The cost is dominated by font embedding and OutputIntent setup — not by the constraint checks themselves. The validators are linear scans over an already-built object graph; the expensive work happens in the writer pipeline regardless. See ISO Standards for what each profile enforces.

Spec compliance advantage

phpdftk’s reader handles both classic xref tables (20-byte entries per ISO 32000-2 §7.5.4) and cross-reference streams (PDF 1.5+). Many PHP PDF libraries throw on one format or the other; phpdftk treats both as primary. This shows up as FAIL cells in the compatibility table on the benchmarks page when other libraries hit input they can’t parse.

Running benchmarks yourself

# Full benchmark suite (writes docs/generated/benchmarks.md)
composer benchmark

# Or via mise:
mise run benchmark

# Single benchmark class
vendor/phpbench/phpbench/phpbench run benchmarks/GeneratePdfBench.php --report=default

The repo-local report at docs/generated/benchmarks.md is what CI publishes to the _benchmarks orphan branch and embeds into the Latest Benchmarks page on every push to main.