I run a WordPress site and I need to change the theme to a new, faster one. However, when I install the new theme and Import demo content, the site doesn't present well at all.

I'm thinking of a way of doing a fresh install without losing my pages and posts. My question is: If I export my content, run a fresh install, and Import back the content, will the post and pages permalinks stay the same? Is this going to impact my SEO negatively?