Problem with colorfabb XT

Hi,
I’m trying to print with XT-filament.
I unloaded the ABS (printing flawless @240-245 deg). Loaded the XT. First it couldn’t put XT-filament through the nozzle at all. With a little force help before the extruder, the filament started flow.

Start printing @240. The extruder can’t push the filament through the nozzel at my print speed (45 mm/s).
If I push the filament by hand before the extruder, it can keep up, but that doesn’t solve the problem…
I tried to raise the temperature to 250 and even 260 deg with same results.

I’m using standard extruder and nozzle (0.35). I have calibrated the nozzle temperature and ABS prints flawless (~same temp).

Is anyone else printing with XT without problem ?
Is the nozzle to small for XT ?
Do I need a E3D v6 ?
Must I lower the print speed ?
Anything other I may missed ?

best regards /Lars