Windows – Webpages open PAINFULLY slow in Internet Explorer on Windows 7

So, it turned out that the "certain sites" were sites that used a secure connection (https) or that had content coming from a secure site (such as google analytics if you use https as prefix in your code). In "Internet Options" i went to "Content" and clicked on "Clear SSL state". This did the job

More detailed instructions can be found here http://support.microsoft.com/kb/967897 where it says "I can't access my bank or other secure websites"

When you connect to a secure website, Internet Explorer uses an encrypted channel that uses Secure Sockets Layer (SSL) technology to encrypt transactions. Corrupted information in the SSL can cause websites not to load correctly. Clearing the SLL state may resolve this problem. To do this, follow these steps for your version of Windows. Windows 8

Swipe in from the right edge of the screen (if you're using a mouse, press Windows logo key+C keys), and then tap or click Search.

Enter Internet options in the search box, and then tap or click Settings. In the search results, tap or click Internet Options. Tap or click the Content tab, and then tap or click ClearSSL state.

Windows Vista and Windows 7

Click the Start button, type Internet Explorer in the search box, and then, in the list of results, click Internet Explorer.
In Internet Explorer, click Tools, and then click Internet Options.
Click the Content tab, and then click Clear SSL state.

If clearing the SSL state does not resolve the problem, the date and time settings on your PC might be incorrect. Some secure sites require that the date and time on your PC match the date and time of the website. To check the date and time, follow these steps for your version of Windows. Windows 8

Swipe in from the right edge of the screen (if you're using a mouse, press the Windows + C keys), and then tap or click Search.

Enter date and time in the search box, and then tap or click Settings. In the search results, tap or click Date and Time, and then tap or click Change date and time. In the Date and Time Setting window, set the current date and time. Click OK, click Apply, and then click OK.

Windows Vista and Windows 7

In Control Panel, open Date and Time. To do this, click the Start button, type date and time in the Start Search box, and then click

Date and Time in the Programs list. Click Change date and time. In the Date and Time Settings dialog box, set the date and time to the correct values. Click OK two times.

If you still can’t access secure websites, get help from the Microsoft Community online.

This MSIE behaviour has nothing to do with (character) encoding. Internet Explorer 11 simply does not recognise MIME types properly.

• MIME handling breaks down: some MIME handling steps have changed in Microsoft Internet Explorer 6 for Windows XP Service Pack 2 (SP2) to enhance security. See also Internet Explorer Policy Settings.
• MIME type detection (so called data sniffing) breaks down as well although it should work in Microsoft Internet Explorer 4.0 and later…

More info and guides in Introduction to Feature Controls, Handling MIME Types in Windows Internet Explorer and Internet Explorer Policy Settings articles.

Links under Ham Radio Fonts are links to true type font files (TTF, primarily binary ones). Their MIME type should be application/octet-stream - default if data is binary.