PersonalizeIQ answers
How much can personalization slow down a click?
Not much. Google counts an interaction as responsive when the page reacts within 200 milliseconds. Heavy personalization scripts that run on every tap eat into that fast.
The number to watch
Interaction to Next Paint measures how quickly a page responds to taps, clicks, and key presses. 200 milliseconds or less is good. Above 500 is poor. Measure it at the 75th percentile on mobile.
Keep the work off the tap
Decide what to show before the shopper interacts, not in the click handler. Send tracking events without blocking the next frame. If a rule needs a network call to react to a click, it is probably too slow.
Source
web.dev, Interaction to Next Paint (INP). Reviewed Sep 23, 2026.