No, it won't. Page speed measuring tools don’t always paint an accurate picture when analyzing scripts like Smartlook. You can often see the same issues with the Google Analytics script. The Smartlook script loads asynchronously, meaning it doesn’t prevent the rest of your website from loading while it downloads. The warnings you see in various page speed tools don’t mean that the Smartlook script slows down your site.
The load time of our script is negligible on most websites. Since all the data flows between the Smartlook script and our server, your server is not burdened with extra data. We take site performance very seriously and constantly optimize the Smartlook script to improve load time. We also use various tools and services like CDNs (content delivery networks) to load our script extremely fast everywhere around the globe.