TinyPDFViewer vs. PDF.js: Which Is Better for Performance?When choosing a web PDF renderer, performance is often the deciding factor. This article compares two popular options — TinyPDFViewer and PDF.js — across multiple performance-related dimensions, helping you choose which is better for your project.
What these projects are
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TinyPDFViewer: A minimal, performance-focused PDF viewer designed to reduce bundle size and runtime overhead. It typically provides essential features (rendering, paging, basic navigation) with a small API surface and fewer dependencies.
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PDF.js: Mozilla’s widely used, fully featured PDF rendering library implemented in JavaScript and WebAssembly. It supports a broad set of PDF features (annotations, forms, text selection, search, complex rendering modes) and is the de facto standard for many web apps.
Initial load (bundle size and parse time)
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TinyPDFViewer’s core goal is minimal footprint. It usually ships a much smaller JavaScript bundle than PDF.js, so initial download and parse times are typically faster with TinyPDFViewer, especially on slow networks or low-end devices.
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PDF.js provides many features out of the box, increasing its bundle size. However, it does offer modular builds and the ability to load parts on demand; still, out-of-the-box PDF.js often costs more in initial load time.
Practical tip: For single-page apps where every kilobyte counts, TinyPDFViewer often has the advantage.
Memory usage and runtime performance
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TinyPDFViewer tends to use less memory because it avoids heavy features (full text layer, advanced rendering options) and keeps fewer caches. This translates to lower runtime memory footprint and generally snappier performance on devices with limited RAM.
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PDF.js maintains more internal state and rendering caches to support features like text selection and search. On large documents or long sessions, PDF.js can consume more memory, but its optimizations (tiling, worker threads) can maintain smooth scrolling and rendering.
Practical tip: For embedded viewers in constrained environments (embedded browsers, older phones), TinyPDFViewer often performs better.
Rendering speed and smoothness
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PDF.js uses worker threads and advanced rendering strategies (progressive rendering, tiling) to keep UI threads responsive. For complex pages with images and vector graphics, PDF.js can offer smoother viewport scrolling and faster progressive rendering.
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TinyPDFViewer, while faster at startup, may render pages more simply. For basic PDFs (scanned pages, text-heavy docs) its rendering can be comparable, but for graphically complex PDFs PDF.js usually outperforms in steady-state rendering.
Practical tip: For long documents with many images or vector content, PDF.js’ rendering pipeline is more robust.
CPU utilization
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TinyPDFViewer minimizes CPU use during idle and simple viewing scenarios because it avoids heavy parsing and feature processing. Lower CPU usage is common during typical navigation.
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PDF.js can use more CPU during rendering and text extraction tasks, but offloads heavy work to web workers where supported, limiting UI jank. Higher peak CPU usage may occur but it’s often well-managed.
Feature-performance tradeoffs
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TinyPDFViewer sacrifices advanced features for performance. If your use-case needs annotations, form filling, text selection, or accessibility support, you may need to add extra modules or accept lower functionality.
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PDF.js includes many features natively; those features add overhead but can save development time and provide a richer UX.
Comparison table:
| Dimension | TinyPDFViewer | PDF.js |
|---|---|---|
| Initial bundle size | Smaller | Larger (modular builds possible) |
| Memory footprint | Lower | Higher (more caching/state) |
| Rendering of complex pages | Good for simple pages | Better for complex/vector pages |
| Smoothness/scrolling | Good on simple docs | Smoother on heavy docs (workers/tiling) |
| CPU usage | Lower in steady use | Higher peaks but offloaded to workers |
| Feature set | Minimal | Comprehensive |
| Accessibility & advanced features | Limited | Strong |
Real-world benchmarks (how to test)
To compare in your environment, measure:
- Bundle size (gzip/brotli)
- Time to interactive (TTI) and First Contentful Paint (FCP)
- Memory usage across a long session
- CPU profiling while scrolling and during page change
- Time to render a page with heavy images/vectors
- Feature interaction latency (search, text selection)
Use browser devtools, Lighthouse, and automated scripts (Puppeteer, Playwright) to collect data reproducibly.
When to choose TinyPDFViewer
- You need the smallest possible footprint and fastest startup.
- The PDFs are mostly simple (text/scans) and don’t require advanced features.
- Targeting low-end devices, limited network bandwidth, or strict performance budgets.
- You prefer to implement only the features you need.
When to choose PDF.js
- You need full PDF feature support (annotations, text selection, search, accessibility).
- Your documents include complex vector graphics or high-resolution images.
- You prioritize robust rendering quality and smoother long-session performance.
- You want a mature, well-supported library with broader community tools.
Hybrid approaches and optimization tips
- Lazy-load the viewer or parts of PDF.js only when needed.
- Use web workers for parsing/decoding where supported.
- Serve compressed PDFs and enable brotli/gzip for JS bundles.
- For PDF.js, build a custom bundle that excludes unused features.
- Cache rendered canvases or use tiled rendering strategies for long docs.
Conclusion
- For minimal initial load and lower memory/CPU footprints, TinyPDFViewer is better for performance in lightweight scenarios.
- For complex documents, feature-rich needs, and smoother long-term rendering under load, PDF.js performs better overall due to its advanced rendering pipeline and worker offloading.
Choose TinyPDFViewer for startup speed and small devices; choose PDF.js for rendering robustness and feature completeness.
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