I developed a page www.protellus.eu.
On banner pane I put a content slider module.
On first visiting some slides appears like small icons in left corner of banner pain instead of normal slide through the whole paine (see attached files).
After visiting page again, slide appears correctly.
Also what I noticed is that sometimes slides in content slider are loading so long.

Please, is there any solution about that.

Hard to say what the problem is. I have loaded the page and the slider shows fine. Maybe the images just didn't load up fast enough before the slide code run. I suggest optimizing the banner image size to improve performance. Try to run the images at https://tinypng.com

Many thanks Andy, will try tinypng.com, hope it will works.