Very slow speed with wireguard over vless

[Epenko1337]

Server speedtest.net result
Client speedtest.net result with wireguard over vless
Client speedtest.net result with just vless proxy

Client configuration for wireguard over vless:

{
    "log": {
        "loglevel": "debug"
    },
    "inbounds": [
        {
            "tag":"wireguard",
            "port": 51820,
            "protocol":"dokodemo-door",
            "settings":{
                "address":"127.0.0.1",
                "port":51820,
                "network":"udp"
            }
        }
    ],
    "outbounds": [
        {
            "protocol": "vless",
            "settings": {
                "vnext": [
                    {
                        "address": "...",
                        "port": 443,
                        "users": [
                            {
                                "id": "...",
                                "encryption": "none",
                                "flow": ""
                            }
                        ]
                    }
                ]
            },
            "streamSettings": {
                "network": "tcp",
                "security": "reality",
                "realitySettings": {
                    "show": false,
                    "fingerprint": "chrome",
                    "serverName": "...",
                    "publicKey": "...",
                    "shortId": "...", 
                    "spiderX": ""
                }
            },
            "tag": "proxy"
        }
    ]
}

Server configuration:

{
    "log": {
        "loglevel": "warning"
    },
    "inbounds": [
        {
            "listen": "0.0.0.0",
            "port": 443,
            "protocol": "vless",
            "settings": {
                "clients": [...],
                "decryption": "none"
            },
            "streamSettings": {
                "network": "tcp",
                "security": "reality",
                "realitySettings": {
                    "show": false,
                    "dest": "...",
                    "xver": 0,
                    "serverNames": [ 
                        "..."
                    ],
                    "privateKey": "...",
                    "shortIds": [...]
                }
            }
        }
    ],
    "outbounds": [
        {
            "protocol": "freedom",
            "tag": "direct"
        }
    ]
}

Wireguard MTU is 1300. What could be wrong? Is it that much cpu expensive operation to route from xray to wg tunnel?

[devopg]

"protocol":"dokodemo-door",
And where does WireGuard fit into all of this?
I don't quite understand your final configuration. If you are using x3-ui, it would be better if you show screenshots.