Windows 7 Outlook 2016 slow for no reason?

Hello guys,

I've got a strange problem with Outlook 2016. I have a PC with 2 user accounts and 2 different Outlook-profiles. "User Account 1" has a normal/fast running Outlook while "User Account 2" has an extremely slow Outlook.

Things I already tried and looked for:

• outlook safe mode -> still slow
  
  
• disable all add-ins -> still slow
  
  
• close all other programs -> still slow
  
  
• delete mails/calendars/contacts -> still slow
  
  
• online/offline mode -> both slow
  
  
• repair pst-files -->there are only ost-files and most of them are new created.
  
  
• disable gpu accleration -> still slow
  
  
• also found this tutorial for slow running outlook but it didn't work
  > GOOGLE "poor outlook 2016 performance blog"
  > CLICK THE FIRST LINK
  
  
• repair office -> still slow

i really hope someone has a solution for this. i'm running out of ideas.

OS: Windows 7 , 32-bit

Have a nice day!