Why does Outlook launch IE in the background?

At my work we are experiencing a issue on our windows 7 machines the 2 Iexplorer.exe processes over time will cause performance degradation to the point a webex will take 5 minutes to open, Once we go in and end all Iexplorer.exe process including the outlook ones everything works normally and is back up to speed, 

This only happens on windows 7 machines, our windows 10 boxes open outlook and its 2 iexplorer.exe process just fine with no issues over time. 

We have had the case open with microsoft for 3 weeks at this point still no luck on the root cause or a fix other then we know its tied to the iexplorer.exe processes as our users have found out and now they just end them to get things working again which in turn makes it hard to get users to work with.... sigh 

I would be ok with a opt in to a version of office / outlook that does not preheat IE since everything was fine up until that change the few second addin wait time is much better then browser and webex performance degrading to a crawl.

over 2 years this has been being called out in way or another maybe preheating IE isnt the best way to make up for slow add-in performance....

 have no legacy apps in the background, go to libreoffice, I would advise.

Haha, good joke. Libreoffice is a big legacy junk, just dig into the source code and read about its history.

It seems, MS uses this approach to render and compose HTML emails. I can imagine, it is a 'lazy approach' instead of having to maintain the legacy outlook render engine, they use the other legacy engine so less code has to be 'legacy'.

MS direction is office365 online, not using locally. I do not expect office locally ever to be improved or rewritten from scratch. 

If that is wished for, work locally and have no legacy apps in the background, go to libreoffice, I would advise.

So this issue is happening with our end users as well however I do not believe it is isolated to just Outlook.  I tested on my own Win 10 64 bit machine and with each launch of an Office 365 App such as word, excel, etc. each app would open 2 instances of internet explorer.  When the app is closed the Internet explorer background process remains orphaned.  We are version 1902 build (11328.20158 Click-to-run). 

This appears to be a bug but would love to know from Microsoft if there are any intended updates since this has been an ongoing issue for well over a year. 

Also please note that these machines that this issue occurs on could be older with Win 8.1 or a newly imaged machine so this sounds like the O365 platform as a whole.  I would not be so concerned with IE launching as a process as a result of the add-ons but need to have these processes finalize as the app closes in order to not be holding resources on the computer.

Another in a long, long,  line of examples of Microsoft  incompetence/dishonesty/deception/general lack of respect.   Pick one or all.  We are currently looking at moving to Apple or Linux.  Tired of wasting time and money with MS.