It is not so much total download time that is important as the time before the first appearance of something the user can read. DO set ALT text for all important images. The second biggest impact on download times is large and complex tables. DO split big tables into smaller ones where possible. DO make sure the top table is a relatively simple one.
Users scan web pages.
They DON'T read them so . . . DO make the words meaningful on their own. This has no meaning other than 'here is a link' which is obvious from the underlining. Link text is also automatically underlined. DO NOT use underline style for ordinary text.