The boost converter is fairly weak. This was known going into this design. However, the LED brightness wasn't ever really calculated and was just assumed it would be kept under control by the specific LED programs in use.
Since per-color gain tuning isn't implemented yet, for now the default global gain is turned down to prevent voltage drop from turning off white LEDs when programs that light a significant number of LEDs are run. If turning up the brightness the white LEDs can still drop.