iPhone 6 Plus did suffer from a lack of RAM from day one though. When I upgraded to the 6S Plus the increase in RAM made a big improvement. I couldn't even switch between Facebook app and Safari and back again without Facebook having to be reloaded on the 6+. It was the 6+ that really struggled, the smaller 6 I don't believe was as bad.
Yeah it was only with the 6 plus to some extent.