The first place to look when trying to make a page load faster is for ways to reduce the number and total size of HTTP requests. The benefits come from the fact that the browser downloads the content in larger chunks instead of spending time waiting for a lot of small round-trips to the server to complete. This is especially beneficial for users with low speed connections such as mobile users.
Resource concatenation is a simple concept that does not need any introduction. This can be done manually but it is preferable to automate this task with a bundling script or introduce a build step for your project. Depending on your development environment, there are different bundling solutions to choose from. If you are using grunt or gulp as part of your development stack, you can use solutions like
grunt-contrib-concat (https://github.com/gruntjs/grunt-contrib-concat) and
gulp-concat (https://github.com/contra/gulp-concat) respectively.