OS: Windows 10
Java ver.: 1.8.0_51 (64 bit)
Processor and GPU shouldn't be an issue, but in the case they are...
GPU: GTX 960 2GB
RAM: 8GB DDR3-1600
Minecarts will only turn in certain directions and not others. The minecart on the slope will not roll down and pass through the east-to-south junction and the other minecart cannot pass through the other way. However, minecarts can pass through the south-to-east junction (in the other included image) without an issue.