使用预览对PDF文件进行密码保护时的长延迟

下面是我创建受密码保护的文件的脚本，但我不知道为什么第一个复选框需要12秒钟才能被单击

不过，第二次单击效果很好

我尝试过几件事，包括：没有成功

activate application "Preview"
tell application "System Events"
tell process "Preview"
    keystroke "p" using command down
    delay 0.5
    tell front window
        repeat until exists sheet 1
            delay 0.5
        end repeat
        tell sheet 1
            click menu button "PDF"
            repeat until exists menu 1 of menu button "PDF"
                delay 0.02
            end repeat
            click menu item "Save as PDF" of menu 1 of menu button "PDF"

        end tell
    end tell

    repeat until exists sheet 1 of sheet 1 of front window
        delay 0.2
    end repeat

    tell sheet 1 of sheet 1 of front window
        click button "Security Options..."
    end tell

    tell window "PDF Security Options"
        set selected to true
        set focused to true
        -- NOTE: for some reason there is a delay of about 12 seconds here, I do not know why
        try
            tell checkbox "Require password to open document"
                click
            end tell
            keystroke VarPassword
            keystroke (ASCII character 9)
            keystroke VarPassword

            tell its checkbox "Require password to copy text, images and other content"
                click
            end tell
            keystroke FixedPassword
            keystroke (ASCII character 9)
            keystroke FixedPassword

            click button "OK"
        end try
    end tell

    repeat until exists sheet 1 of sheet 1 of front window
        delay 0.2
    end repeat

    keystroke "g" using {command down, shift down}
    repeat until exists sheet of sheet 1 of sheet 1 of front window
        delay 0.2
    end repeat

    delay 0.5
    keystroke SaveFolder
    delay 0.5

    click button "Go" of sheet of sheet 1 of sheet 1 of front window

    set value of text field 1 of sheet 1 of sheet 1 of front window to FileName

    click button "Save" of sheet 1 of sheet 1 of front window   
end tell
end tell