between SEO and Speed optimization, one question please !

Hi, i recently read some articles about how optimize a WP theme for SEO and speed. So i pick up two conclusions, in order to:

1- increase Speed you have to limit php querys, by changing this ones into static content …
2- and for SEO you must have a nice “headers” work in your template files.

The article sayd.. that :
* the “Blog Title” must be set to <H1> only in front page, as the others tiles must use the rest
* in others pages, like in a “post-page”, the page-title must use <h1> header and titles, like the Blog title and others, must uses the rest of the headers.

the only way i know to change the header of somthing (like the blog title) from one page to another is by using a “conditional tags” so a php query, right?

it is not a little contradictory ?

thanks for your advise…