Either your podcast feed is very large or it's loading very slowly.
Here's some things to try:
1.) Log in to your WordPress site
2.) Go to PowerPress >> Settings, Advanced Mode >> Feeds tab
3.) Check the boxes next to:
*Do not allow other plugins to modify podcast feeds.
*Accelerate feed
*Feed Episode Maximizer
4.) Click the Save Changes button at the bottom of the page
Post a respons here when that's done and I'll take another look at the feed.