Friends, do we have some sort of cache on PCV , i am implementing on one sandbox account and it takes 1 hour to reflect changes

Well, yes there are various levels of caching that can be applied. If you're using a sandbox, I would turn off CDN caching. You can also use the manual cache invalidation process for the application to clear the cached version of the thing you're testing (eg the items API). And make sure you disable caching in your browser and that you do a hard reload each time you refresh