why does it take a long time to get my email on windows live? I get it on my yahoo mail 5 minutes before windows live.

Recently, I have been getting my Windows Live  email late.  I have different 4 email addresses. I use Windows Live so I can get all 4 emails at once. But lately, it take 5 minutes or longer to get my email thru Windows Live. I can check my Yahoo email & get it right away, but not on Windows Live.  The reason I use Windows Live is so that I don't have to sign in/sign out for each different email address. That takes a lot of time. So, what is the tie up between these 2 email programs?