Here are a few tips to help optimize for Google Ads export.
1) Group items together and in the in5 export dialog in the Advanced section, choose Export Groups as Images. Only group items that do not contain interactivity. That will reduce the number of images in the output.
2) Optimize the images. The Pro plan lets you do this automatically upon export (also in the Advanced section of the dialog), and the Gold plan lets you use Enhanced optimization which is even stronger.
3) Choose one of the Continuous Scroll page formats — it requires less CSS and JS than the Slider formats.
4) If you know your content is going to be viewed online (which is the case with pretty much all Google Ads), you can remove the local copy of jQuery (assets/js/jquery.min.js) and re-zip your package. The jQuery file is about 94kb uncompressed. The reason this won't harm anything is because in5 uses an online link to jQuery (cached on most people's browsers) and the local copy is only there as a fallback for offline use.*
* Version 3.5 (or higher) of in5 now automatically omits the local copy of jQuery when exporting to the Google Ad output format, so no need to do step #4 manually.