Hi Kenneth Black,
Yes, using app/plugins it will make website slower so some of the theme integrate promotion bar as default theme settings so please check admin panel first, if not then hire some developer to add those features
Here are couple of apps you can add if its works for you:
You can try Simple Header Bar. I have built it to easily put announcements in the header of my clients’ stores. I needed something super simple, easy to customize and without any ads or nagging me to get a paid version. The app is 100% free and I am planning to keep adding new features.
Hi Kenneth, Sarosha here from Aiva - Popups, Slide-ins and Bars!
Many Shopify stores use the Promotion and Announcement bar features our design solution offers. You may want to check it out ? You can customize the placement + branding of the campaigns & it's free to use.
Our app is built in a way that it will only display campaigns after your website completely loads. Feel free to reach out on Live Chat if you have any questions or need assistance setting up.