In my web.config file, within the appsettings section, I have defined several keys such as companyname, companyaddress, etc.  In my master page code behind file, in the Page_Load area I have associated the appsetting keys with some labels that I have setup in the master page to represent the various pieces of data.

In testing the pages of the site out that use the master page everything seems to be working just fine, the various bits of data are coming in as they should be set at the values from the web.config file.

The site(s) that I am doing this on are small in terms of the number of pages to the site and the user load viewing the site isn't that large either.  What I am wondering is if the approach I have taken is all right performance wise or should I do something different?

it's perfectly fine to do it how you are explaining.

As long as you're not storing any sensitive information in the web.config appsettings section, you can do this no problem.

Otherwise, I would suggest storing encrypted values in the web.config, and have a worker class decrypt the info before setting the labels.

 In General,

Put information in the web.config that could change by the Configuration ( changes in Hosting, Client, Environment) and/or it used multiple times in application.

Encryption is subject of Security, it always better to keep, but important thing how important for us it to preserve.

Thanks to those who replied to my message providing the confirmation that the way in which I am using the appsettings section of the web.config file is in line with what it was intended to do.  Rest assured the manner in which I am using it contains no confidential or secret information as my intent is to use it for information within site content that can change such as company name and address information so that there is one and only one place this information has to be changed and once done the site content itself sees this change and no further modification to site content would be necessary.