Predictive prefetching (similar to the work here, but more aggressive) did impact the servers on a zillion-visitors mobile commerce site at first, but it's fine now. Tuning helps.

More than scaling, the larger headaches come from migrating all your existing logging to account for preloading versus impression hits.

Oh, good point. CPC is based on the user clicks, i.e., fetching.

Yes. I wonder too what the additionnal load is, I don’t have numbers for now.

I work for a gazillion pageviews website. I'm discussing this library with my team I'll let you know. :P

Thanks, much appreciated!