Thank you for the honest answer. I have a couple of remarks, hope you will not consider them "trolling".
- you said "Don't show unique icons" works around the issue completely, thereby providing a workaround;
"Don't show unique icons" is not a workaround. I would rather live with 10 seconds lag than without unique icons. When you're working on a big project, you have lots of objects with long names, and the list looks like this:
ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa... ObjectNa...
It takes ages to find the right object, as you need to click every one to see its full name. And it makes it much harder to read event sheets. So no, this is not a workaround, it's disabling a very important feature.
And anyway, this only helped me, others say that event dialogs are still slow even without the unique icons.
then this seems to have a relatively minor impact
Trust me, it's not minor. Try using a software for 10 hours a day where almost every action causes a lag, sometimes small, sometime big and you'll understand.
And I'm sick or rebooting my laptop...
But most importantly - if you strongly believe that this is a windows issue, can you please log a bug report with Microsoft?
I think it's your duty as a developer, since your software product is hitting this bug and affecting us, end users (who paid you money for said software product).