Quick response while passing ...
The problem you have is not so much the motor as the driver. The TB6560 driver works well at the lower speeds as your Ali machining testifies, but to get higher speed you probably need a higher voltage. Machines I've overhauled that are using the '24V' solutions for CNC perform considerably better when driven by a '48V' driver setup. While the TB6560 driver is rated up to 36V, you need a little headroom, and while a 30V supply will give a little more 'umph' it's not going to do much better than you are currently seeing.
As you say "I am cutting Al and plastics at 100-200mm/min without problems at all." and this setup is really happy at those speeds. Changing motors may give a little better performance, but to double the speed you probably need to change the drivers for higher voltage ones.