Basically, your acceleration is far too low for your current feed rate. The tool cut path (white lines) is basically showing you what the CV calculation is doing. The more accel you can configure your motors to have, the better the tool path will follow the programmed path. I typically keep upping my acceleration until the drive faults or the motors start stalling/losing steps then I back off 10%. Be careful, as the load on the tool will also affect the point at which the stepper motors stall.
If your system will not allow much more acceleration, then the ONLY thing left is to slow the feed rate to accommodate the slow accel settings.
Steve