- Our key design challenge was to make sure people would notice relevant results without being distracted
- We tried a prototype where we waited for someone to stop typing before showing results, which did not work. We realized the experience needed to be fast to work well
- One solution to serving 5 to 7 times as many results pages for each query performed in Google Instant was deploying new caches and introducing user-state data into our back-ends to keep track of the results pages already shown to a given user
Definitely worth a read for a bit more info from the Google perspective.