These 10 best practices will ensure that your site is running at full speed.

1. Caching

If someone put a gun to my head and gave me one way to improve a site’s performance it would be caching. Caching buffers your pages in the server’s memory and so avoids database/server roundtrips, resulting in faster response times and reduced server loads (and thus reduced hosting charges). If your site gets less than 1000 pageviews per day you probably wont see much speed improvement from caching. Your CMS should support caching (if not you should move on ASAP) and you should turn it on. For WordPress, WP Super Cache is the standard and still the best caching plugin.
Still not convinced? Take a look at the response times for a site where I was turning caching on and off, all the spikes in the graph are when I had caching turned off.

2.Use a Content Delivery Network (CDN)

CDN’s were previously very expensive to use with high monthly minimum’s but several new entrants (notably AWS CloudFront and RackSpace Cloud Files) have made it affordable for smaller sites to use CDNs. CDN’s work by caching files at different geographical (‘edge’) locations and therefore reducing the lag users who are geographically far away from the server experience. The larger the files, the greater the benefit of using a CDN, video files are a must but you should also consider hosting images and even css/js files on a CDN.

3. Place Scripts at The Bottom of the Page

Html pages load sequentially, so a reference to an external javascript files placed above the body tag will need to be loaded before the page’s content. This can make the page loading appear sluggish.
Even scripts such as javascript files for AJAX operations used on the page can be placed below the content. This will mean users cannot interact with the site content when it is first displayed, but research by Facebook showed that users prefer to see content as soon as possible even if it cannot be interacted with.
Scripts such as Google Analytics code should always be placed at the bottom of pages.

4. Use External CSS Files

Pages which are heavy with Html load a lot slower than pages which reference CSS for styles, positioning etc. For starters CSS is more compact than Html for positioning and styling page elements, furthermore if it is placed in an external file it will be cached on the user’s browser so that it will not need to be loaded for subsequent page loads in the same session.
You should always review the outputted source code (ie view the rendered page and then look at the source code by right clicking and selecting View Source or similar command) to look for Html which can be replaced by CSS.

5. Host Files on a Separate Domain

A quirk of most browsers is that they can only make a two simultaneous requests to a domain. If your page has several images and external files (such as CSS or javascript files) these must be queued and requested two at a time. Hosting images or files on a separate domain (or a subdomain) allows the browser to make most simultaneous requests and render the page quicker. This is also an additional reason to use a CDN as the files will always be on a separate domain.

Next, Part II of Best Practices to Speed Up Your Site

Provided your web site/application is running on the Windows stack now (Windows Server/IIS/ASP.NET) it should be compatible with the cloud offerings from Rackspace Cloud, Amazon, GoGrid and others. In this article I will focus on the big two cloud providers (Rackspace and AWS) as well as the new Windows Azure service which could be consider as worthy rivals to  traditional Windows Hosting.

Rackspace Cloud provides two Windows cloud hosting offerings, Cloud Sites and Cloud Servers. Cloud Sites is a standardised product which provisions a website with a fixed windows setup – Windows Server 2008/IIS 7 and ASP.NET (2.0 and 3.5 both supported). If you run a website powered by a Windows based content management system (CMS), or customer relationship management system the Rackspace Cloud Sites will probably be the best option. Cloud Sites only provides FTP access to the server and no Remote Desktop access to the server is possible. Cloud Sites basic package starts at $150 per month plus $10 per month for a 100MB SQL Server database.
If the application setup is more complicated and operating system access is required, Rackspace Windows Servers will be the best option which starts at about $112 per month for 2 GB RAM /  80 GB Hard Drive server (smaller instances are also available). This service is currently in beta and a major weakness is that this does not come with a SQL Server installation and users are required to make their own arrangements.

Amazon AWS has been offering Windows cloud hosting options since early 2009.  1.7 GB of memory / 160 GB (1 core) EC2 instance are priced at $80 per month. SQL Server is available, however it does get expensive as a lease on SQL Server standard edition starts at $750 per month.

The new entrant to Windows cloud hosting is Microsoft with its new Windows Azure service. As noted above, all Windows applications will need at least some modification to run on Azure. The biggest change is probably with SQL Server, where  the cloud variant (SQL Azure) has numerous incompatibilities making migration a challenge at best. SQL Azure databases are priced at $10 per month for 1GB and $100 per month for 10GB.
Windows Azure pricing is slightly different from Rackspace and AWS which bundle a the RAM/CPU/Drive space in a virtual server package. Windows Azure is broken out between compute ($84 per month), storage ($0.15 per GB per month), storage transactions ($0.01 for 10,000 transactions) and data transfer at $0.10 in / $0.15 out per GB. This makes comparisons difficult in pricing, however Azure looks to be slightly more expensive than AWS and cheaper than Rackspace (the $10 per month SQL Azure instances can make Azure a lot cheaper as n0 equivalent exists on the other providers).
For an overview of Windows Azure see Windows Azure First Impressions , or Who Will Use Azure

Summary

Which of the providers is best really depends on your needs. If it is a simple website then Rackspace Cloud Sites is definitely the way to go. If you have a more complex application (which for example runs windows services or requires access to the OS) then AWS is probably the best bet. Azure promises to be the ultimate windows cloud with features such as SQL Azure databases which can be scaled up on demand, although it does have compatibility issues with existing windows apps and is still in its infancy (having just been released in February 2010).

(note – I have used monthly charges to compare pricing although all the above providers bill the services hourly)

I’ve had a good chance to try out the Cloud Sites service and my experiences are below:

Gettting Started

Signup is very easy and I was up and running with 15 minutes. The main control panel is very clean and easy to navigate, performance is good and there are no slow loading pages.

Site Setup

Rackspace Cloud Sites supports both Windows Server/IIS/ASP.NET  and Linux/Apache/PHP . You can mix Windows Server and Linux sites on a single account although you are not able to configure the setup such as the version of PHP etc (if you need to configure the setup you should consider Rackspace Servers).

Adding a site is relatively easy although it isn’t quite a clean as it could be since the interface caters for users setting up their own sites and for resellers setting up sites for clients (if you are setting up your own site just ignore the different ‘plans’ you are presented with as each site’s resources comes out of a single pool and there is no throttling of sites which breach their plan limits).
It only takes about 5 minutes to have the site up and provisioned and ready to go.

Databases

Rackspace Cloud Sites supports MySQL and SQL Server. There is no control over the version or setup of the databases, at time of writing MySQL 5 and SQL Server 2008 (Web version) are being offered.

MySQL databases are free whereas SQL Server databases cost $5 per 100MB and $10 for 200MB. The SQL Server pricing is definitely on the high side and the size is quite limiting.

Adding a database is a snap, once again the interface is clean and intuitive and the database should be ready within a couple of minutes. Databases are closely associated with sites so you will first have to select a site and then add a database in the ‘Features’ tab.
Once setup, databases can be administered using phpMyAdmin , Rackspace Cloud Sites provides a link to the phpMyAdmin although you will have to enter your login details to access phpMyAdmin. If you prefer using MySQL administration sorftware on your local PC (such as MySQL Administrator or MySQL Query Browser) you can connect to your database. If you are using SQL Server you will need to connect via SSMS.

Monitoring / Reporting

The monitoring and reporting is quite limited. Only a single page of data is provided which provides data on the Bandwidth DiskSpace and Compute Cycles and gives a breakdown per site. However there is no costing information or a breakdown by date/time. Also no information on downtime, response time etc.
You will definitely need to monitor your sites by yourself and should subscribe to third party services such as Pingdom.

Tools

Tooling is very limited and you will need to write your own routines or utilize third-party tools (Rackspace Cloud has a listing of third-party tools on the site).
Backup is a major omission, the files are backed up and available on FTP for download. There are several backups made per day and they are available for a month, however the timing of the backups cannot be configured. Importantly there is no backup for databases and you will need to backup up your databases by writing a cron (crons are supported) or using a third party tool.

Performance

Looking at the response times of my sites (previously they were hosted on mid-spec’d dedicated box at Server Beach) they are very comparable at approx 500ms load time. I noticed some timeout issues when I first migrated to Rackspace Cloud Sites , I contacted support and they informed me that another account was running some long running queries which slowed down the cluster (really thought they would be implementing more rigorous resource throttling) but this got sorted out very quickly.

Support

Email and live support is free (unlike with Amazon) and the quality and responsiveness was excellent. Live support was available within 5 minutes and emails were normally turned around within 2-6 hours. All problems were dealt with (although in truth I didnt have many complex requests).