How I Shaved 10 MB Off My Portfolio in One Command

PageSpeed Insights had been staring at me for weeks. Desktop was holding at 91. Mobile was stuck at 63. I'd already fixed the obvious stuff — non-blocking fonts, preconnects, fetchpriority on the hero image. But there it was, every single run: Improve image delivery — Est savings of 985 KiB Nearly a megabyte of wasted transfer, just from six project screenshots. And that was just the images visible above the fold. The full list across all projects was worse. The culprit: every image I'd ever uploaded through the Django admin was a PNG. Some of them were over 1 MB. WebP would have cut most of them by 80%. I knew this. I just hadn't done anything about it. So I wrote a management command to fix the backlog, and then made the model auto-convert on every future upload so I'd never have to think about it again. The Problem With PNGs in a Portfolio When you're building a portfolio, you screenshot your work and drag it into the admin. That screenshot is usually a PNG — lossless, full-size, straight from your display. Nobody optimises it because the admin accepts it and it shows up fine in the browser. But "shows up fine" isn't the same as "loads fast." A 1.4 MB PNG of a law firm homepage does not need to be 1.4 MB. Served as WebP at quality 85, it's 175 KB. Same visual result. Eight times smaller. Multiply that across 28 projects and you're looking at tens of megabytes that mobile users on slow 4G are downloading just to scroll past thumbnails. The One-Time Backlog Fix: A Management Command First, I needed a way to convert everything that was already in S3. A management command was the right tool — it runs in the production container with full access to the Django ORM and the configured storage backend, so it can read and rewrite files without needing to know whether they're on S3, local disk, or anywhere else. # backend/projects/management/commands/convert_images_to_webp.py from io import BytesIO from django.core.files.base import ContentFile from django.core.management.b