Category not showing in the header?

Are you looking at the same site and switching themes or looking at two different sites?
If they are different sites
- are they on the same server?
- are the number of database records the same?
- when was the Last time the database was compressed?
- how much memory do the servers have?
- what are the image sizes on the pages
- is the data on either site on a CDN
- are the settings for the caching plugin set to the same values
- how many comparison tests have you done 1, 10, 50, 100
- were they done at the same time.
- how many other sites are running on the servers?

As you can see from my questions, there are a lot of variables that effect speed.

If you are basically unsatisfied with the results, maybe this isn't the theme for you