我正在学习如何使用Async和Await。我编写了这段代码来获取一个网站，然后每隔一秒就在Imports System.Net
Imports System.IO
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Timer1.Start()
End Sub
Private Async Function FetchData(uri As String) As Task(Of String)
Using wb As New WebClient
Dim stream As New StreamReader(wb.OpenRead(uri))
Return Await stream.ReadToEndAsync
End Using
End Function
Private Async Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
RichTextBox1.Text = Await FetchData("http://someurl")
End Sub
End Class
上写一次。问题是，如果网络速度减慢，页面的提取也会减慢，并且UI会暂时冻结。这是代码：
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