Topic: why does the mme/directx driver work better as the rme asio driver?

i have a fireface ucx interface and get alot of pops and crackles even at 2048 samples buffer size while working in ableton live. i thought that's because of the big projects and all the cpu heavy vst-plugins i use and that i need a new workstation soon but when i change the driver type from asio to mme/directx everything works flawless even with much more vst-plugins used. i'm working with a dell precision m4800 notebook, i7 4980mx, 32gb ram, win10. i already tried all usb ports and a different usb cable, the newest firmware and driver of the ucx are installed. i was used to work in 96000hz sample rate when i bought the ucx many years ago, but i already changed it to 48000hz to lower the cpu load a few years ago. in totalmix fx loopback is activated on one channel, but that's it.
any ideas?