How does SlashImage optimize GIFs?
2 min read · Last updated June 2026
Yes - SlashImage optimizes GIFs. It compresses the GIF and keeps it as a GIF, and it also makes a WebP version for delivery: animated when your GIF is animated, static when it is a single frame. It never makes an AVIF copy of a GIF, and it never resizes one.
What you get
- An optimized GIF. SlashImage runs your GIF through a GIF optimizer and serves the smaller result. Animation is preserved.
- A WebP version. Browsers that support WebP get the smaller WebP; everything else gets your optimized GIF. The WebP is animated when your GIF is animated, and static when your GIF is a single frame.
- No AVIF. SlashImage does not make an AVIF version of a GIF. If you have Generate AVIF turned on, it is simply skipped for GIFs.
Full-size only, never resized
SlashImage optimizes the full-size GIF only. It does not touch the smaller thumbnail copies WordPress creates, because WordPress flattens GIF thumbnails to a single still frame, so there is no animation to keep at those sizes.
It also never resizes a GIF, even when Resize large images is on, because resizing would flatten the animation. Your GIF is sent for optimization at its full dimensions.
Already-optimal GIFs
If your GIF is already about as small as it sensibly gets, SlashImage leaves it unchanged and the SlashImage column shows Already optimal. That is common for GIFs that were optimized before you uploaded them, and it is not an error.
Very large GIFs are skipped
A GIF with too many frames, or dimensions that are too large, cannot be processed. SlashImage skips it and shows:
This GIF is too large to optimize.
This is a permanent skip for that file - the GIF is left untouched and is not retried. To optimize it, reduce its dimensions or frame count and upload it again.