You are not buying this theme. This is only a preview for 5sec Category Search WordPress plugin which works exactly the same in all themes.

Will this plugin slow my site down?

No. The plugin simply modifies your search query. So, until a user makes a search absolutely no overhead is made.

Will this plugin slow my site’s search?

Searches made while the plugin is enabled are definitely more complex than ones made without it. However, unless you have +10 thousand posts there shouldn’t be any noticable speed change.

Can I search multiple categories at once?

No, at the moment that feature is not supported.

My search page is no longer working. I get some PHP errors.

The plugin can only work on WordPress v3.x. Are you sure you’re not running v2.x?

Some taxonomies are missing from my dropdown

You have to manually select what taxonomies are shown in the dropdown. This also implies if you add a new taxonomy – after adding it, go to 5sec Category Setting and select it to appear in the dropdown.