I didn't confuse them - I explicitly distinguished between them. Scalability is a category of performance - it is performance at scale. Most of these suggestions may help with individual browser loading - but will not make a significant difference in scalability. However, the pretense for the investigation was the high level of traffic that was imminent - a scalability challenge.
You can have a slow-loading site that will scale to hundreds of millions of users.
You can have a very fast site that will die under a thousand users.