If I add a second domain, will it affect the performance of my other site?

[muhittin]

If I add another domain to my account, will my other site’s performance decrease?

[adisp007]

If that new domain will use same resource (htdocs folder) with current domain (Parked Domain), it won’t affect your other site.
But if they use different resource, it will affect your site performance.
It isn’t only your domain, other users domains too. Because you are in the shared server.

[MAHOfficial]

If by that you mean you add another domain in your hosting account then it will surely affect your other site performance as both sites will use same resources and they will reach limit soon. I will recommend to get another account for your site as you can have total of 3 free hosting accounts.

[Admin]

All resources like CPU, RAM, hits, processes and so on are limited on the account level. So if you have multiple domains or multiple websites on the same account, they share the same pool of resources. And if you exhaust these resources, both websites will be affected.

Fortunately, you can create up to three hosting accounts, and all three accounts have individual resource pools. So if you want to host two websites with us, you can just create a second account for the new website.