1. BTEC NCF Dip in Comp - Unit 15 Website Development Lesson 05 – Website Performance
Mr C Johnston

2. Learning Outcome
Know different factors which can affect the performance of a website
Understand how each factor can affect the performance of a website and steps which can be taken to limit the affect

3. Starter
What factors can make browsing the internet an unpleasant experience?

4. Factors Affecting Website Performance
Where scripts run
on the web server – server-side scripts
on the local client machine – client-side scripts
Browser compliance
which elements are supported by different browsers
Sever-side factors
bandwidth availability, number of hits, file types to send
Client-side factors
upload and download speeds, browser, cache memory, processor speed, interactivity.

5. Client vs Server Side Scripting
Client side scripting are scripts which are run on the computer which is displaying the website
These add some sort of interactivity to the website
Calculating prices when ordering multiple goods
Handling image galleries
Messages that popup and indicate forms are not filled out correctly
Server side scripting are commands run by the computer hosting the website
More complex algorithms and often server side scripting is based around databases
querying them to generate dynamic webpage's
processing login requests
processing data collected from a form

6. Client Side Scripts vs Server Side Scripts
ASP, CGI, PHP
Script

7. Review Questions What are the pros and cons of using scripting?
Is client side scripting or server side scripting better?
If you have to use scripting what is best practice?

8. Browser Compliance
Different browsers handle HTML, client side scripting and embedded elements differently
Its important to check compliance before rolling out your website
Can provide alternative code for different browser so the same outcome is achieved

9. Supported Media

10. Supported Plugins Browser ActiveX NPAPI Java Gears RSS Atom Other
Google Chrome No
Dropped
Yes ?
Internet Explorer
Microsoft Edge
Mozilla Firefox
Opera
Safari
Partial

11. Review Questions
How can you ensure that your website will work on different browsers?
Plugins don’t seem to be supported anymore by the major browsers
Why has this happened?
What impact does this have on web developers?
What impact does this have on web users?

12. Discuss…
Client Side Factors

13. Discuss…
Server Side Factors

14. User / Client Side Factors
Your Internet Connection
Type, speed, ISP, Local popularity, Distance from exchange,
Hardware Using To Browse
Type, Specification, Size of monitor (resolution), How interact, Age, Connection method (wired/wireless), Type of router,
Browser Software
Choice, Age, Speed of Page Delivery, Support features, plugins, security policy,
Security Software
Features, firewall settings,
Other Home Factors
Other users, position of router, house construction, other signals

15. Server Side Factors Server Internet Connection Server Hardware
Upload speed vital, DSL so is at least same as download speed
Server Hardware
Type, Specification, Age,
Number of sites running on server
Few paid for hosts are dedicated probably several sites running on same – is the servers load balanced properly??
Number of hits – especially simultaneously
Files which make up the site:
Lots of small files better than few big ones
Optimise images so are correct size – web browser shouldn’t download image with large dimensions and shrink,
Correct file type with compression – graphics, audio, video
Selective use of media (flash, video, sound) – correct format, compress, steam video if possible (progressive download rather than waiting for full file)

16. Activity
BTEC (2010) Book – p8-11
Link #1, Link #2, Link #3
Factors
Set your page to landscape and create a table similar to the one below which can be used to summarise the different factors which affect website performance
For each factor suggest how they can impact browsing and steps which can be taken to minimise the impact
Factor
Description
Impact on Browsing
Steps to Minimise Impact