My laptop have two network adapter:one is wired lan, while the other is wireless lan. Now I connect ipv6 using wired lan and ipv4 using wireless. The web page seems to get something wrong. It load slowly. However, if I disconnect one of the adapter(anyone of ipv4 or ipv6), the web page load fast as I expect. Why does the odd phenomenon occur?
Because you are essentially specifying two gateways to the internet and the system does not know which one to use. You could try this experiment: remove the gateway setting from one of your two connections. Now try loading the web page. Everything will load fast.