I recently uploaded a website to a new 123-reg server on a single WP installation (www.moseleycoachsales.co.uk). I had developed the site on my own hosted multisite environment (http://test.digitalgroupmedia.com/moseley/).
I had a nightmare uploading the website as the standard wordpress xml export/import facility that had always worked for me kept crashing crashing. In the end I managed to get the website live using this method (http://matteth.wordpress.com/2012/01/12/exporting-a-site-from-multisite-to-single-installation/)
The live website is now very sluggish and nowhere near the speed it was on my test environment. I don’t know if this is down to the new server, or if something has occurred in the website move (perhaps database related) that has created the issue?
I’m not great with MySQl so don’t really have the skill to diagnose this issue (if it even is the issue) and would really appreciate some help.
Your site is very, very heavy at 4+ megs. Lighten it up; see http://gtmetrix.com/reports/www.moseleycoachsales.co.uk/eyz4qxQx
Fix the code errors, such as not specifying image dimensions, not correctly scaling your images, not optimizing your images, setting browser caching and expires headers, etc.
Your site speed has very little to do with one 404 for one style sheet. Use Firebug with Firefox, or use the developer tools in Chrome or Safari or IE to see what’s loading on your site.
Your database may be oversize from revisions and your theme may be using more than the average number of queries. Use http://wordpress.org/plugins/debug-queries/ and http://wordpress.org/plugins/rvg-optimize-database/
And, every inexpensive host out there is slow. Check http://www.google.com/search?&q=123-reg+slow
In your head you have
<link rel="stylesheet" href="css/bootstrap.css">. This is trying and failing to load bootstrap.css using a relative URL.
I would install the debug bar plugin and try to see what is going on, but if that’s not in your comfort zone, first step should be to contact your host and ask if they can help.
opening your home page is consuming around 3,5 mb bandwidth, you must reduce it.