The JavaScript ecosystem continues to see developers creating native implementations of traditionally compiled libraries, with fast-png offering a pure JavaScript solution for PNG encoding and decoding. However, community discussions reveal significant concerns about its performance claims and security considerations.
Performance Reality Check
Despite its name suggesting superior speed, community benchmarks indicate that fast-png may not live up to its performance promises. Multiple developers have shared comparative analyses showing that alternative libraries outperform it by significant margins. One developer noted that png-tools is about 2-6x faster than fast-png for encoding, while also offering additional features like multi-threaded encoding and cancellation support. The underlying compression implementation, which relies on the pako package, shows notable performance gaps compared to native implementations, with benchmarks revealing that zlib's deflate operation is nearly twice as fast, and its inflate performance is approximately three times faster than pako's JavaScript implementation.
Not a single benchmark on the page... Just sloppy TBH.
This sentiment reflects a broader community frustration with libraries that make performance claims without providing supporting evidence. Several commenters pointed out that naming a library fast creates expectations that should be backed by comparative data.
Performance Comparisons
Compression Performance (from pako benchmarks)
- deflate-pako: 10.22 ops/sec
- deflate-zlib: 18.48 ops/sec (approx. 1.8x faster)
- inflate-pako: 134 ops/sec
- inflate-zlib: 402 ops/sec (approx. 3x faster)
Alternative PNG Libraries Mentioned
- png-tools: 2-6x faster than fast-png for encoding
- fpnge: Fast C++ encoder with lower compression ratio
- stb_image: Single-header image library for game development
- wuffs: Google's memory-safe media format decoder
Security Considerations for JavaScript Decoders
Beyond performance concerns, security experts in the discussion highlighted potential risks when using JavaScript-based decoders for untrusted inputs. While fast-png's pure JavaScript implementation reduces some attack vectors compared to native code wrappers, the robustness of its Inflator implementation and other components remains a concern. The community discussion points toward Google's Wuffs project as a potential solution for safer image parsing, designed specifically to address common vulnerabilities in media format decoders.
Alternative Implementations
The discussion revealed several alternatives worth considering depending on specific use cases. For JavaScript environments, png-tools appears to offer better performance with additional features. For C++ developers seeking alternatives to libpng, fpnge was recommended as a very fast png encoder with slightly lower compression ratios but significantly faster operation. The stb_image single-header library was also mentioned as a widely-used solution in game development, supporting multiple image formats beyond PNG.
The conversation around fast-png highlights an important lesson for developers evaluating libraries: look beyond marketing names and carefully assess actual performance characteristics, security implications, and feature sets before integration. While pure JavaScript implementations offer convenience and broad compatibility, they often come with meaningful performance trade-offs compared to native alternatives.
Reference: fast-png: PNG image decoder and encoder written entirely in JavaScript