Will Full Page Zoom slow down my page loading times?

No, Full Page Zoom does not have an impact on the page loading time. The zoomed images are loaded in the background once the page has been loaded.

However, the size of the zoomed images may affect the app responsiveness if they are too big. You can limit the size of the zoomed images at the app preferences page, please check the related articles for more information and/or see the image below for your reference.