Actually there are only a few browsers that you need to test with. IE9 is first, most people use it and it does not follow W3C standards to a T. Followed By Firefox this browsers is growing fast in userr base, it is a W3C compliant browser (this also includes chrome). Chrome is based on Firefox to some extent. Your next browser should be Safari, cant forget those folks over at apple, From what I know of Safari is that it does follow W3C standards.
IE issues that kills development is, not all versions of IE are the same. Just because it works in IE9 does not mean it will work in IE8 or lower. Also You may have to write more code to work around these issues, which will extend your development time. IE has been the biggest headache for most developers, all I can say is good luck with it.
I do use the Web developer tool bar for firefox and it is showing some errors in CSS (to many to count) and javascript(4 errors). These errors are based on the W3C standard and maybe needed to work in IE. That's what makes development so difficult now days.
Outside the lesson though everything seems to be working just fine here at my end. I am tethered to my phone via wireless and almost no speed issues. Most of my speed issues are caused by 3G not the site. Nothing can be done about that part other than using a DSL or Cable service which I can not afford. Some things in Korea cost more and that is one of them.
Anyhow I hope this helps?