What are some important optimizations that can be made to a website to reduce the loading time?
See Question&Answers more detail:osWhat are some important optimizations that can be made to a website to reduce the loading time?
See Question&Answers more detail:osRemove/Minimize any bottlenecks on the server side. For this purpose, use a profiler like Xdebug or Zend Debugger to find out where your application is doing expensive and slow operations. Implement caching where possible. Use an OpCode Cache. If this still isn't fast enough consider investing in more CPU or RAM or SSDs (depending on whether you are CPU, IO or Memory bound)
For general server/client side optimizations, see the Yahoo YSlow! User Guide.
It basically sums it up to:
- Minimize HTTP Requests
- Use a Content Delivery Network
- Add an Expires or a Cache-Control Header
- Gzip Components
- Put StyleSheets at the Top
- Put Scripts at the Bottom
- Avoid CSS Expressions
- Make JavaScript and CSS External
- Reduce DNS Lookups
- Minify JavaScript and CSS
- Avoid Redirects
- Remove Duplicate Scripts
- Configure ETags
- Make AJAX Cacheable
- Use GET for AJAX Requests
- Reduce the Number of DOM Elements
- No 404s
- Reduce Cookie Size
- Use Cookie-Free Domains for Components
- Avoid Filters
- Do Not Scale Images in HTML
- Make favicon.ico Small and Cacheable
Also see the comments contributed below, as they contain some additional useful information for other users.