slow to navigate away from folder that has 25000+ files

[sean-e]

Describe the bug
There is significant lag after navigating away from a directory than has a large number of files.

To Reproduce
Steps to reproduce the behavior:

1. Enable Details View
2. Open a folder that has 25000+ files
3. Go up a directory (to the parent directory, assuming it doesn't also have a huge number of items)
4. Significant lag is experienced

Expected behavior
No lag after step 3.

Version (please complete the following information):

• Explorer++ version: dev x64
• OS: Windows 10 x64 1903