TinyImage includes a Downsizer feature which allows you to automatically resize (and lightly compress) any Figma image fills on your layers to their actual layer size. This is useful if you've originally imported high resolution images to your Figma file, but then shrunk the layer dimensions down to be much smaller (with the original large image file still being used).
One common case of this would be adding a large image from Unsplash (or another stock photo site/plugin), the resizing that layer to be used as a much smaller "card" or "avatar" image. This can cause the performance of your Figma file to slow down; so using something like this downsizer feature will help save file size and improve page performance in your Figma file.
Using the Downsizer feature to optimise image fills on your page
To get started with downsizing your Figma fills, you can click on the Downsizer button in the TinyImage header.
If you didn't have any layers selected when opening the downsizer feature, it will automatically scan every layer on the current page in your Figma file for any that contain image fills.
Selecting the image fills to downsize
Once the image fills have loaded, you can select which you would like to downsize by checking/unchecking them in the list. You can also quickly narrow down the images included in the list by clicking on them in your Figma page.
If you're unsure which fill relates to which layer, you can click on the Image icon button in the list, which will instantly zoom and scroll to that layer on your Figma page.
Downsize your fills
When you're happy with your fill selection, you can toggle the resolution that you would like your Figma image fills to be downsized to; by default this is set to @2x, which means your image fills will be proportionally downsized to be exactly twice the size of the Figma layer that they're being used in. You can toggle this down to @1x, which will resize the image fills to be exactly the same size as their Figma layer, but won't be as sharp as the @2x option.
When you're ready, click on the Downsize Figma Image Fills button to start the downsize process. TinyImage will automatically detect if an image needs to be downscaled or not; any that require downsizing will be resized (and lightly compressed), then automatically replaced in your Figma layers. Once every image has been processed, you'll be able to see the total amount of size you've saved in your Figma file.