Page optimization means one page (URL) of your website being optimized once. If your page has versions (e.g. mobile and desktop), then this would be two optimizations, one for each version of the page.
You need NitroPack if you need to boost your website loading speed, improve your website conversions, and improve search engine page ranking. NitroPack is Google-PageSpeed-focused speed optimization tool.
NitroPack is a different service than CloudFlare. NitroPack is focused on making your website load fast by improving the Google PageSpeed score of your website. CloudFlare does only limited number of optimizations on your website, whereas NitroPack optimizes all Google speed recommendations.
NitroPack is very efficient and helpful for big traffic campaigns on your website. It makes your website skip the server work on each visitor landing on a public page, hence makes your server use much less CPU and memory for serving the same visitor base.