In reply to Francisco Rojas.

The loading speed on the front end depends on a number of factors. The first and most important is the theme that you use. The second most important factor is what plugins you are using. Many will load additional scripts and styles on the front end.

This is a much larger topic, which is also specific to individual sites, than what we can realistically dive into here in the comments. There are many friendly volunteers who can help over at WordPress support.