EE show loading gif when search

> url goes to homepage and shows white page for a while

Not sure exactly what you’re describing there, but when you perform a search, it will go to an interstitial page (Messages > User Messages in System Templates), that then redirects to the user’s search results. This prevents your search results page from being susceptible to DDOS attacks, while also temporarily caching those results for the visitor who performed the search.

So if you are seeing your homepage, you might have some .htaccess redirects interfering with form submission. If you’re seeing a white screen, it could be that you have removed content display from your User Messages template. A third possible reason is having error reporting disabled, or being logged out, and there’s being a fatal PHP error, but that would prevent the redirect from occurring, so isn’t the most likely reason.