Benchmarks

@pyyupsk/fdu is designed to be lightweight and performant. Here's how it compares to other popular date libraries.

Bundle Size Comparison

Library	Minified	Minified + Gzipped
@pyyupsk/fdu	9.0 KB	3.13 KB
Day.js	7.0 KB	2.9 KB
date-fns	~70 KB (full)	~17 KB
Luxon	256 KB	~70 KB
Moment.js (deprecated)	~290 KB	~72 KB

Bundle sizes are approximate and may vary depending on which functions you import. @pyyupsk/fdu is tree-shakable, so you only pay for what you use.

Performance Benchmarks

Performance tests were run using Vitest Bench with Vitest 4.0.15 and Bun 1.3.3 on 2025-12-05.

Comprehensive Benchmark Results

Operation	@pyyupsk/fdu	Day.js	date-fns	Luxon	Speedup vs Day.js
Date Parsing	2.88M ops/sec	2.06M ops/sec	134.1K ops/sec	413.1K ops/sec	1.40×
Date Formatting	955.1K ops/sec	548.7K ops/sec	398.0K ops/sec	626.1K ops/sec	1.74×
Date Manipulation	3.87M ops/sec	965.2K ops/sec	3.28M ops/sec	449.1K ops/sec	4.01×
Date Comparison	20.17M ops/sec	1.53M ops/sec	4.92M ops/sec	6.98M ops/sec	13.18×
Complex Workflow	549.8K ops/sec	245.9K ops/sec	415.5K ops/sec	143.1K ops/sec	2.24×
Batch Operations (100 dates)	9.4K ops/sec	5.3K ops/sec	5.7K ops/sec	2.8K ops/sec	1.79×

What's Being Tested

Date Parsing: Parsing ISO 8601 date strings (2025-09-30T14:35:45.123Z)
Date Formatting: Formatting dates with pattern YYYY-MM-DD HH:mm:ss
Date Manipulation: Adding 1 day to a date
Date Comparison: Comparing two dates with isBefore()
Complex Workflow: Parse, format, and manipulate operations combined
Batch Operations: Creating and formatting 100 dates

date-fns uses parse() with format string, while Day.js and fdu support direct ISO string parsing.

Running Benchmarks Yourself

You can run the benchmarks yourself to verify the results:

# Clone the repository
git clone https://github.com/pyyupsk/fdu.git
cd fdu

# Install dependencies
bun install
# or
npm install

# Run benchmarks
bun run bench
# or
npm run bench

Methodology

All benchmarks were conducted using:

Hardware: Intel Core i5-12400, 10GB RAM, WSL2
Runtime: Bun 1.2+ / Node.js 22+
Framework: Vitest Bench (experimental benchmarking feature)
Test Data: ISO 8601 date strings (2025-09-30T14:35:45.123Z)
Iterations: Each test runs with multiple samples to ensure statistical significance
Warmup: Each benchmark includes a warmup phase to optimize JIT compilation
Libraries Tested:
- @pyyupsk/fdu v0.0.0-beta.3
- Day.js v1.11.18
- date-fns v4.1.0
- Luxon v3.7.2

Results may vary based on your hardware and runtime environment. Run the benchmarks yourself for accurate measurements on your system.

Key Takeaways

Bundle Size: @pyyupsk/fdu (9.0 KB / 3.13 KB gzipped) is comparable to Day.js (7.0 KB / 2.9 KB), significantly smaller than Luxon (256 KB / ~70 KB) and date-fns (~70 KB full)
Fastest Comparisons: Date comparison operations show the most dramatic speedup, making fdu ideal for sorting and filtering date collections
Manipulation Speed: Adding/subtracting dates is significantly faster than Day.js and Luxon
Consistent Performance: All operations benchmark faster than Day.js, with the table above showing exact speedups
Day.js Compatible: Despite the performance gains, the API remains fully compatible with Day.js

@pyyupsk/fdu provides excellent performance while maintaining a small bundle size, making it ideal for both client-side and server-side applications.

Real-World Performance

Beyond synthetic benchmarks, @pyyupsk/fdu's immutable design and minimal overhead make it particularly efficient for:

Server-side rendering - Fast date formatting for timestamps and logs
Data processing - Efficient batch processing of date operations
Client applications - Small bundle size improves initial load times
Real-time apps - Low overhead for frequent date updates