The privacy policy is here, on the extension privacy policy page :
https://addons.mozilla.org/fr/firefox/addon/yay-another-speed-dial/privacy/

I don't use the built in sync functionality because you just can't know when it's effectively syncing or not. You can find yourself making modifications, closing Firefox and nothing synced... So I ended up creating my own system for better reliability.

You can set the animation delay to 0 so they all appears at the same time or completely turn off animation

Thanks for your feedback and suggestions and I hope you will enjoy this extension! :)