ID 386851 - [C] UI: Disappearing panels when scrolling using Compare on a large sequence

Customer reported version
Flix 6.1.2

Customer reported platform
macOS 10.14

Steps to reproduce
1) Create a Sequence Revision with a significant amount of panels (for example 160 panels)

2) Select several panels (for example 60)

3) Click on Make a new version at the bottom of the Tool Bar 

4) Save the Sequence Revision

5) Open the Compare Tool and select the initial Sequence Revision to compare the two. Scrolling through the Panel Browser with the Compare Tool activated causes the Flix Client to lag, and some panels disappear and reappear randomly

Expected behaviour
Scrolling through panel browser to be smooth, and all panels to show

Actual behaviour
Scrolling through the panel browser lags, some panels don't show straight away but reappear while scrolling

Reproduced by support
6.2.2 - macOS 10.13
6.1.2 - macOS 10.14 - Windows 10
6.1.1 - macOS 10.14
6.1.0 - macOS 10.14 - Windows 10

Unable to reproduce bug in:
6.0.5

Earliest version tested
6.0.5 - This issue doesn't appear in this version and has regressed