Introduction
This document contains information on the various factors from the user and the server of a website, and their overall effects on the performance and running of the website. It will include the individual effects of each piece of hardware and what it does to help with the performance of the webpage. The effects of malicious entities like viruses and botnets and how they affect the server and its running.
User side factors that influence web performance
Viruses: If the user’s computer is infected with a virus it is able to reduce the speeds of the internet connection and can overload the processor so it works harder. This then has to calculate the information for the website and other task it has been forced upon by the virus causing loading times to increase.
Each virus falls under a different category, each category does a different type of malicious activity.
Trojan horse in computing terms is a non-self-replicating malware program that contains malicious coding. This program, when it is executed by the user will carry out various tasks that have been determined the Trojan’s nature. Trojan’s are typically used in a way such that the victim suffers from data loss, data theft, and even possibly damage to the system. Trojan’s can infect the victim’s computer for a various number of reasons. The virus is able to force the machine into a botnet system which is part of DDOS attack. Some attacks that can be unintended or used out of pure intent of being malicious is to crash the victims PC, corrupt data and even format storage disks. Key loggers are often used in Trojan form.
Worms are another type of virus that can infect a victim’s computer. The worm virus is designed to cripple computer networks and systems. One of the traits of the worm allows it to search the internet to find a target system running an application it is able to infect. Both worms and Trojans are able to open a backdoor route into personal data.
Botnets are a problem, these groups of computers are under the control of criminals, each and every computer within the botnet group has been infected, this could have been from a Trojan. Once compromised the victim’s computer is then known as a bot. The criminal at the centre of the operation is also known as a bot herder. Botnets are generally used to commit DOS/DDOS attacks and other tasks such as sending spam emails with malicious code to infect more computers to add to the botnet.
This is a diagram of the running of a botnet.

Image found at: http://www.windowsecurity.com/img/upl/botnet_rysunek_011128349033015.JPG
The best way to cure your computer from a botnet infection is to completely format the hard drive/s.
Phishing is another malicious problem. Phishing is the act of attempting to gain information like usernames and password combinations and billing details. This is done by gaining trust with the victim via communication over the internet. This communication is done through popular social sites. Phishing emails are part of the phishing scam, the phishing emails may contain a hyperlink to a malicious webpage that looks exactly the same as a legitimate website.

Example of a phishing email.

Image found: http://upload.wikimedia.org/wikipedia/commons/d/d0/PhishingTrustedBank.png
Internet speed: The user’s internet speed can drastically affect the times taken to load a website as it affects the amount of data that can arrive at once different connection types have different average speeds for connecting to the web.
There is a varying choice of connection types and speeds that come with it. Here is a list of connection types and their matching speeds. * Dial-up: >56 Kb/s * ISDN: 64 Kb/s – 128 Kb/s * ADSL: 128 Kb/s – 8 Mb/s * Cable: 512 Kb/s – 20 Mb/s * Satellite: 1 Mb/s – 16 Mb/s * Optical fibre: 44 Mb/s – 40 Gb/s
The optical fibre speeds vary on the tier type they are, the different levels of cable each have different operating speeds.
AMD Processor: http://images.tweaktown.com/imagebank/ap2955_intro.jpg
AMD Processor: http://images.tweaktown.com/imagebank/ap2955_intro.jpg
Processor: If the user’s computer has a low speed for the processor, this will cause the website to take longer to load as the data has to be calculated to form the website on the users screen. If the user is multitasking it will slow down the loading times as well.
Browser: There are many different types of browsers that conform to the same method of interpreting and displaying the code. There is a slight difference in performance from browser to browser.
Cache Memory: The cache memory means that when the user visits a webpage, the browser stores a copy in the temporary internet files, when the user re visits the page the browser loads the cache memory and checks for alterations. The large the cache the quicker the website will load, the negative effect is that it can slow down the user’s computer.
Plugins: Some websites require certain programmes to be installed to view the website. A common example is the Flash plugin. Flash is a vector animation software originally designed to create animations for display on web pages.
Monitor resolution: The monitor’s resolution can affect the users performance on the web, a larger resolution is better for the website in general as it is able to display how it was intended and the view of it is clearer. The larger resolution requires a heavier load on the processor and usually a graphics card will help process the web page onto the monitor.

Server side factors that influence web performance
Hits: A hit is when a visitor clicks and views the website, software is available that can run from the web server. Each hit can be defined as whether or not it is unique. Each unique hit can be tracked and define when the user visited the website and a variety of other information.
Bandwidth: Bandwidth is the amount of data that can be transferred from the server to the user per second. Having a larger bandwidth allows more visitors to access the website efficiently at any one time.
File Executions: The are files that have to be executed before the user can view the webpage; this is so that they can instantly view images and videos as soon as the page loads. This is the same for some internet games. They usually require Adobe Flash or Oracle Java.
DOS/DDOS: A Denial of Service attacks is an attempt to render a machine or network resource unavailable to the intended users. A DOS attacks are implemented by forcing the targeted computer to reset or to consume its resources so it runs too slowly to perform its intended tasks. The DOS/DDOS attacks involves sending huge amounts of data packets at the target machine, the high amount of packets sent overwhelm the target and can cause it to slow completely.
Server Performance issues: There are a variety of different performance issues that can affect web hosting servers. A different number of factors have to be taken into consideration. Depending on the problem there sometimes can be simple solutions to the problem at hand. One solution could be to change to file formats in use to a type that is more compressed increasing loading time by reducing the amount of data needed to be transferred. By increasing the loading speeds from that method, the client is then able to view the content of the webpage quicker. The increased speed can be vital to businesses as some people may get bored waiting for a page to load.
Another method to speed up loading times is to keep the data together for certain parts of the website, this means that the files needed to be sent to the user are easily located and sent to the client.
DDOS attacks cannot fully be stopped, instead they are usually mitigated. This means that the attack is spread out across several servers to dampen the effects. DDOS mitigation companies work by ‘scrubbing’ the data requests and packets that flow through them, any data attempting to reach your website has to pass through this service, the suspicious IP’s and ones that have already sent malicious packets are then blocked from future access.
File types
Images: The main types of file formats used in website design are the JPG and GIF formats. The GIF files are generally used for work with vector images, the vector would be useful for something like a company logo. This characteristic means that they have a smaller file size and are able to be transferred quicker. The other main file format used is the JPG format. Jpegs are usually used with bitmap images such as that of photos, illustrations and other raster images.
Animations/Games: Most online flash games and animations are in the SWF (Shockwave Flash) file type. The SWF file is created using flash software that has been created by Adobe. The SWF is popular for online flash games such as bloons tower defence.
This is an image of the popular online flash game Bloons Tower Defence 5. The flash game can be found at: http://ninjakiwi.com/Games/Tower-Defense/Play/Bloons-Tower-Defense-5.html

Image found: http://schnapzer.com/uploaded_images/original/5a6c8-btd5%20bloons%20tower%20defense%20daily%20challenge%20airplane%20ship%204.jpg
Videos: Websites and businesses are able to benefit from the use of video media. People are also able to generate revenue from online videos from an advertising slot at the start of each video, this can be found on the popular video sharing site called YouTube. This website allows users to upload videos to their own “channel” in which other users are able to view their content. There is a variety of formats that can be used on the web, but the most efficient file type is the mp4. MP4 videos retain a decent quality whilst not taking up much disk space. The average 10 minute video rendered in 720p takes up just over 1.5GB of data.
Conclusion
I have found that there are a various number of reasons as to how and why the performance of web pages is affected. I have also found out some of the steps that can be taken to improve the performance issues.
References
Wikipedia. (12/12/13). Trojan horse (computing). Available: http://en.wikipedia.org/wiki/Trojan_horse_(computing). Last accessed 16/12/2013.
Wikipedia. (15/12/2013). Phishing. Available: http://en.wikipedia.org/wiki/Phishing. Last accessed 16/12/2013.