Hello, @sahanaashu
Theme affects the site speed if you compare it with a completely simple default WP theme because it calls more scripts, styles, makes requests but if you set up cache plugin, optimize images, optimize pages content and server settings it does not affect speed critically.
Anyway, we are working on theme improvements and plan a major theme update with speed improvements in July-August. If you are not satisfied with the theme speed we are ready to give you refund.
Regards