I suggest that in your case you are not able to see the updated content in the public website as the server is still displaying the cached version of the page. Restarting the server forces the cache invalidation since you are restarting the application as well, and Sitefinity retrieves the updated content from the database.
You may set up your project to run in a load balanced environment following the instructions in this article
from the Sitefinity documentation and use the Sitefinity's cache invalidation mechanism. You may also find additional information on this issue in the following forum post
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system and vote to affect the priority of the items