All of you should take a look at their system load while having those problems. Ist the cpu (or even just a single core of it) at 100%? Ist the GPU utilized or just on low use? Enough memory is available, how much is used? If you do that you would also immediately see if an iGPU is at 100% and the dedicated videocard is not used at all. That might help tracking down the problem. Just complaining about low fps and keep stating "but my hardware should be able to handle it" will not help anybody.
Even taskmanager could show that, but you should look at while the game is active. A second monitor is usefull. Otherwise try a tool that logs the usage into a file or shows it ingame as an overlay, e.g. HWInfo64 or MSI Afterburner.