The improved PWM phase logic in the 0_15 branch should be extended to ESP8266 as well. This entails:

• Upgrading the vendored PWM library with the NMI interrupt fix to use https://github.com/esp8266/Arduino/blob/master/cores/esp8266/core_esp8266_waveform_phase.cpp as a base, instead
• https://github.com/Aircoookie/WLED/blob/72455ccde1f35c390e86a1038d2c2fd63d5e86fb/wled00/bus_manager.cpp#L596 transition to use startWaveform instead of analogWrite.

Adding an issue entry to track that I plan to work on this.