The purple color in FB4 is an indicator of delayed data from software to FB4. The typical reasons are
- overloaded CPU by complicated content OR big number of projectors.
- network infrastructure.
- CPU power management. MS try to keep the planet and use pretty aggressive CPU speed decrees. .
The answer on question in menu Tools -> FB4 Data transmission diagram, and Core monitor diagram. I recommend to compare diagrams in idle state, small loads, and timeline where you see "all pink". In case of CPU problem you will see long duration of calculation Usually it should be between 0,1...2 ms. I guess you will see around 5 or more. So, Core monitor is an answer.
Best Regards,
Alexey