Steps to reproduce:

1. Open Unity Editor;
2. Create new project;
3. In the Search field of the Project window type any search request returning lots of Free and Paid assets (for instance, 'Terrain assets');
4. Scroll down to the top of the search results ('Paid Assets' should be displayed);
5. Scroll up until 'Free Assets' assets appear in search window (notice that 'Paid assets' files should be visible too);
6. Observe tab icons.

Actual result:
Tab icons flicker when Free and Paid assets are visible at the same time (see attached gif video). Maybe caused by neverending updates of both asset types, which somehow creates race condition.
Several conditions to reproduce this issue:
- The layout scale of asset store tab icons should be relatively big (70% or bigger);
- Project tab should cover less then 50% of the screen.

Expected result:
Tab icons should not flicker when Free and Paid assets are visible at the same time.

Notes:
- Reproduces in 5.4.0b3, 5.3.1f1, 5.2.0f3, 5.1.3f1.
- Reproduces on both OSX 10.11.3 and Windows 10.