Batch Screenshot Optimisation: Numbers
Screenshots for documentation pages load slowly because nobody optimises them. A typical macOS Retina screenshot of a browser window comes in at 800 KB to 3 MB as PNG. The same image as WebP at quality 85 is 60-200 KB — a 4-10x reduction with no visible degradation.
The SnapForge `optimise` command processes a directory of screenshots and outputs WebP files: `snapforge optimise ./raw-screenshots/ ./docs/assets/`. It runs parallel conversion workers (one per CPU core), preserves EXIF metadata, and produces a summary with per-file size reduction percentages.
Actual numbers from a documentation sprint last quarter: 340 PNG screenshots, 2.1 GB total. After optimisation: 318 MB WebP. Page load time for the slowest documentation page dropped from 4.2 s to 0.6 s on a simulated 4G connection (Chrome DevTools throttling).
The quality 85 setting is my default after testing. Quality 80 saves an additional 10-15% file size but introduces visible banding on screenshots with gradients (most UI shadows). Quality 90 adds 25% file size over quality 85 with no perceptible difference on screenshots. 85 is the sweet spot for documentation use.