In wordpress, theme or templates are plays an important role. When you choose the theme for your development you should aware of its load time, speed, and ratings etc.
Theme or template is nothing but the frontend design of your website. A design that has been coded badly, or uses images throughout the design, will add unnecessary weight to your page. It is not uncommon for some WordPress themes to be a few megabytes in size. Such a design could add a few seconds to your page loading time.
Choose a design that has been optimized for desktops, tablets and mobile devices. Search engines favor responsive designs as they ensure all pages have the same URL, however adaptive designs that were created specifically for mobile phones can improve a mobile user’s experience considerably.
Unfortunately, most theme developers optimize their theme demo website using caching and content delivery networks. This makes is difficult to know how quick a WordPress design is before using it yourself.
And when we buy that theme or design, the load time of wordpress website which we using that design become more as compare to actual theme demo. So please check theme or template and then buy.