Windows 8.1 mail- 100% CPU usage

Hello,

I am testing Dell Venue 8 Pro. Overall great device and great system, however, I found very annoying bug:

Windows mail app with few mail boxes (4 Outlook.com, 1 Gmail, 1 IMAP) it may take up to 20 seconds to switch from one mail box to another (or even from one folder to another). I found that CPU usage goes 100% at these moments. I did ran app repair, regular disk cleanup- no success.

Is at any other possible ways to fix it?

Thanks.