Why android webview is much slower than the native android browser?

In my application, i have some external urls to load, for which i am using a custom webview. but the performance of this webview is very very slow. If i open the same url in native android browser, it works fine. but in the webview, it just takes a lot of time to load the page. Is there anyway that the performance of a webview can be enhanced in terms of loading a webpage time? Help is always appreciated.