Designing a website that looks pretty is always important, but a website's load time is also a huge factor that will affect your visitors and your search engine standings.
I use Pingdom Tools to analyze bottlenecks in the sites I build to make sure that there's not one competent that's blocking others from loading. The load time that Pingdom Tools shows is unrealistic because they're using a very high-speed server connection, but it's useful for seeing where your server is struggling.
One way to get your pages to load faster is to load fewer components and keep the size of files small (loading fewer images and CSS files will help visitors load pages faster, and serving CSS inline will reduce the number of requests for more files on the server
Another thing you can do to speed up your pages is to offload images, javascript, and CSS onto a CDN - a CDN is a network of servers which will cache these files and serve them to our visitors from a server closest to the visitor. Not only is it faster for a visitor to load files from a server that's geographically closer to them, but this will also offload your main hosting server so you can handle more visitors more quickly.