site speed

I found my site’s speed become slow (when it load the images)after I change my theme to seledad,how could I fix it?

It depend what’s causing it - that is a very reputable theme from a power elite author so it seems unlikely to be that unless it has not been optimised?

Are all images saved for web?
Have you reduced/removed the pages/code you don’t need?
Are the CSS/JS minified?
Is this decent hosting or entry level shared?