This document provides an overview of factors that affect website performance and techniques for improving performance through caching. It discusses how browser requests work and what HTTP headers can indicate about caching. It also outlines different caching options like browser caching, network caching using proxies and CDNs, and server-side caching using Memcache, Varnish, and opcode caches. Specific techniques for Drupal sites are also mentioned like caching views, entities and blocks. Performance monitoring and testing tools are listed at the end.

1. PERFORMANCE
AN OVERVIEW
HAVE YOUR CACHE AND EAT IT TOO
CreatedbyTonyAslett/@taslett

2. PERFORMANCE
Time taken to render in abrowser/device.
Neo, follow the white rabbit.

3. AFFECTING PERFORMANCE
Network speed
Server response
File size
Number of requests

4. BROWSER REQUEST
1. User: requests apage from the browser
2. Network: DNS finds the server and sends request
3. Server: responds to the page request, generates page.
4. Network: the page is returned.
5. Browser: Renders the page, pulls the files (requests) together

5. HTTP HEADERS
Headers are sentto and from the server with the request.
Tellpoints alongthe path of the requestif cache can be used.

6. REQUEST HEADERS
Browser, user agent
ip address
Compression support, gzip
Cache-control
Cookies
Referer

7. RESPONSE HEADERS
Last-modified
Expires
Cache-control
E-tag

8. SAFE TO CACHE
Anonymous traffic
Scripts and stylesheets
Images

9. BE WARY OF CACHING:
form, postdata
logged in users
User specific content/blocks etc.
Dynamic content
HTTPS SSL

10. GOOGLE HTTPS EVERYWHERE
Google is encouragingthe use of https byincreasingranking
HTTPS as arankingsignal
http://youtu.be/cBhZ6S0PFCY
possible rewrite of cachingrules
No supportfor SSL in varnish

11. CACHE LOCATIONS
Browser
Network: proxy
Server: database, memory
Code

12. BROWSER CACHE
Fast, no download
Headers cache-control:max-age-?
From the second resource load
Use CDNfor re-useable externalresources

13. NETWORK CACHE
Proxy
CDN: ContentDeliveryNetwork, cloudflare
Closer to the browser/user
Operamobile turbo
Cloud Browsers, Maxthon

14. SERVER
Watch CPUand Memoryusage, new relic
Opcode cache, APC
Memcache
Varnish
nginx
SPDY

15. APC
PHP is converted to opcode (computer readable) on the fly
APC stores files as opcode in memoryfor reuse
Significantimprovement
PHP 5.4?has it's own opcode cache

16. MEMCACHE
Keyvalue stored in memory
Works wellwith specific table data
Replaces cache tables

17. VARNISH
Sits before the web server
Veryfast300X

18. CODE DRUPAL
Track slow queries
Avoid excessive loops
Use drupal_static
Cache Views, entities, Blocks blockcache_alter
Static files and content, Boost

19. FILES
Limitnumber and size
Compress
Allow caching
Don'tdelayrendering

20. PERFORMANCE TOOLS
Find your bottle neck and testyour solution.

21. BROWSER TOOLS
inbuiltdeveloper tools.
extensions e.g. pagespeed, yslow
Network requests, file sizes, headers...

22. TESTING/REPORTING TOOLS
ab Apache bench
JMeter
Webmaster tools
Whatdo you use?