[Plugin: W3 Total Cache] Not able to rebuild the sitemap

i am using w3cache and Google XML Sitemaps plugins when the both plugins are active its taking so much time to rebuild a sitemap and even im facing problem in publishing/updating a post,its taking too long to get published/updated.

My primary concern is with sitemap. whenever i disable w3 total cache within 2 sec of time my sitemap is getting updated.but when the w3total cache is on its taking around 200sec to get updated. can any one pls help me !