Amazon Connect - Lex - DTMF slow, but voice input quicker

Hi, I have configured the Lex and Connect to play this following prompt. The voice input, it recognize it quickly within 3-4 seconds. But for the DTMF input, it takes 7-9 seconds, which is a huge delay. Any idea how can I improve the DTMF response quicker?

"Thank you for calling XYZ company. For English, say English or press 1. For other languages, say Other or press 5. To repeat this menu, say repeat or press star."

The session attributes are,

"sessionState": {

    "sessionAttributes": {

        "x-amz-lex:allow-dtmf-input:Repeat:Repeat_Slot": "True",
        "x-amz-lex:allow-audio-input:Repeat:Repeat_Slot": "True",
        "x-amz-lex:dtmf:max-length:Repeat:Repeat_Slot": "1",
        "x-amz-lex:allow-audio-input:Language_Selection:Lang_Select_Slot": "True",
        "x-amz-lex:allow-dtmf-input:Language_Selection:Lang_Select_Slot": "True",
        "x-amz-lex:dtmf:max-length:Language_Selection:Lang_Select_Slot": "1"
    },

"interpretations": [

    {

        "nluConfidence": "1.00",
        "interpretationSource": "Lex",
        "intent": {
            "name": "Language_Selection",
            "state": "ReadyForFulfillment",
            "slots": {
                "Lang_Select_Slot": {
                    "value": {
                        "originalValue": "1",
                        "interpretedValue": "English",
                        "resolvedValues": [
                            "English"
                        ]
                    },
                    "shape": "Scalar"
                }
            },
            "confirmationState": "None"
        }
    },