Although some user reported page speed performace improvements on version 4, my out of the box demo got really bad result on GtMetrix. Webmaster Tools also reported high response time pages in my sitemap.
GtMetrix:
Page Speed Grade: F
Yslow: C
Page load time: 6.44s
WT: Some URLs listed in this Sitemap have a high response time.
Do you have the same problem? Did someone speed improvements for version 4 like in this post for version 3? Please share if you have any idea.