In basic terms, HTTP requests are made by browsers every time they need to fetch a file (of any kind) that has not already been requested and consequently cached (excepting users who disable caching). This includes CSS, JS and images (including any that are called by the CSS or JS rather than the HTML files).

This is why we typically follow this best practice:

- Use only one or two stylesheets and keep conditional stylesheets to a sensible minimum. Never more than one stylesheet - plus any conditionals - for the index page.

- Use one or two JS files and if you use a library (as most of us do now) call it from Google APIs instead of your own server.

- Minify all code when it is ready to be published. This means removing any unnecessary spaces, returns, empty lines, etc. Minfiying tools and websites are widely available.

- Learn how to write really efficient code that does what you want with less. Use a good JS library for that purpose. It applies to PHP as well.

- Be careful with CSS structure - don't repeat declarations unnecessarily by keeping specificity to a minimum.

- Avoid calling files with @import if at all possible. Evidence shows that it is less efficient.

- Use a good quality hosting provider whose servers are reputed to be quick and reliable. Particularly important if there is a lot of server-side code (eg. PHP).

I always advise against cheap hosts that offer unlimited storage and/or bandwidth because you are competing against websites that, for one reason or another, demand that kind of freedom.

You have to question whether a cheap host can afford to invest in the kind of infrastructure that is needed to make such offers without noticeably impacting on performance for all of its customers while more expensive hosts set restrictions. Experience has shown that it's wise to avoid "cheap with no limits".