To improve the performance of a SharePoint site, there are many ways to achieve it. I will list down the list of steps to be taken care while designing a SharePoint page.
  1. Less Usage of Images in Home Page
  2. Ensure that Blog Cache is enabled
  3. MDS - Minimal Download Strategy which is a new feature in SharePoint 2013.
  4. Optimize HTML markup.
  5. Use consolidated images and files; for example, combine multiple CSS files into one, and combine images into an image strip or cluster.
  6. Use compression (crunch) techniques.
  7. Optimize the SharePoint list views.
Refer : Designing pages for quicker downloads (SharePoint Server 2010)