Since Google's introduction of Heavy Ad Intervention, ads can be blocked by your browser if they require too much bandwidth or CPU usage. Google estimates that only 0.3% of all ads falls into this category though so don't worry, it's not a widespread issue.
One important thing to be aware of is that CPU usage is individual and based on the amount of CPU your device is using compared to the capability your device has in total. Normally older devices have a much lower CPU capability and therefore ads in Chrome are more likely to be blocked for people seeing the ad on an older device.
Another reason not to worry is that Bannerflow's ads are built in such a way to minimise the effect and footprint they have on your browser. Images are cropped and compressed, fonts are subsetted and CPU usage should always be kept at a minimum.
However, if you by any chance would encounter a situation where one of your creatives is blocked due to high CPU usage, you could consider the following:
If you're using multiple CPU based widgets (such as "Fireflies", "Water" etc), try to remove one or a few of them.
If you are using multiple SVG images, try replacing them with PNGs – SVG images are great for quality and file size but browsers are in general having a bit of a struggle rendering them (compared to e.g. PNGs).
If your design rely on a vast amount of animations and/or transitions, try to reduce that amount.
As always, if you need any help or guidance, contact our support or your dedicated success manager.