When Yahoo! unveiled its new e-mail browser, some users experienced problems with slowly loading messages. According to Yahoo!, the likely culprit is a Web browser that doesn't have caching enabled. Internet Explorer saves caches of various Web pages so that you don't have to download them each time you visit, but rather you can use the information already on your hard drive. In order to make Yahoo! Mail run faster, you'll need to make sure caching is enabled.
Launch Internet Explorer.
Click "Tools" then "Internet Options."
Click on the "Advanced" tab.
Uncheck the box beside "Empty Temporary Internet Files folder when browser is closed." You'll find this setting under the "Security" heading.
Click on the "General" tab.
Click "Settings," found under the "Browsing History" heading.
Click the radial button for "Automatically" under the "Check for newer versions of stored pages" heading.
Change the number in the "Amount of disc space to use" to at least 50.
Click "OK," then "Apply," then "OK."