When Google looks your site it has a "crawl budget" that is the bot has a limit on the amount of resources it is allowed to use to index your site, and (here we go again) adverts and link banners are going to use this up, possibly to the detriment of your own content.
So, apart from the usual questions about meta tags and keywords on your site you need to ask your web guy or gal about scripts, image compression and banners, especially if these are being loaded remotely from another site. Every call your site makes for information or resources uses up the precious budget Google has allowed for you.
So here are some basics.
- Compress all images including header and backgrounds, down to the absolute minimum without loosing quality.
- Cut all adverts, banners and remote resources to the minimum. Do you really need this advert with its heavy slow loading images for someone else on your site?
The last is particularly important when considering mobile access. some 20% of all smartphone users use ad blockers, so will not see some of these banners anyway (we do), your site however will still try to load them, with more delay.
Google now takes page load speed into consideration, and while this may not be a top priority, anything you can do to gain an edge must be worth at least investigating.