Slow performance with Webadi download after 12.2.8 upgrade

Hello Experts.

We are upgrading from 12.1.3 to 12.2.8. We are having issues while downloading Standard webadi template after upgrade. The issue is not consistent. We have several Windows7/Excel 2016 and Windows10/Office365 clients. Download worked in some client machines but taking more than half hour in some clients. When compared between two windows10/Excel365 clients having same excel & IE settings it works in one (downloads immediately) while it is taking more than half hour in another client.

I have gone through several oracle notes with no luck. Earlier, we had server level performance issues  and users unable to login when webadi was running.  To resolve the performance issue we had to set the profile "BNE: Enable OOXML Standard"  value to NO. If we set this to Yes, download works fine. But getting a hit on the overall application performance. Even with this profile set to No, it is working fine in some machines. Checked all the IE and excel settings and they seem to be okay. Need to know what is causing this inconsistency and slow performance