Hi there,
As @liaifat85 
states , lower it. for me and others lurking…here is why and what it does.
- Connection interval
The time between data transfer events between the central and peripheral devices. The connection interval is set by the application, and the devices use it to decide how often to communicate. Lower connection intervals increase speed and decrease latency, but they also increase power consumption.
HTH
GL 
PJ 
I setup two,
Gets pretty good just chilling…
Not connected, waiting for connection.
Not connected, waiting for connection.
Not connected, waiting for connection.[BLE ] BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP : Conn Handle = 0
【connect_callback】 Connected to XIAO BLE Central
Sensor Setup Started.
Pressure Sensor...
Pressure setup okay.
PPG...
Could not communicate with the sensor!
Configuring Sensor....
Error configuring sensor.
Error: 255
Accelerometer...
Accelerometer okay!
Sensor Setup Ended
[CHR ] Notify 2 bytes
Sensors Values Sent
[BLE ] BLE_GATTS_EVT_HVN_TX_COMPLETE : Conn Handle = 0
[CHR ] Notify 2 bytes
Sensors Values Sent
[BLE ] BLE_GATTS_EVT_HVN_TX_COMPLETE : Conn Handle = 0
[CHR ] Notify 2 bytes
Sensors Values Sent
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0
Sampling Rate: 22.50 packets/second
Bit Rate: 43920.00 bits/second
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0
[BLE ] BLE_GATTC_EVT_HVX : Conn Handle = 0