This plugin slows down Homebridge
<!-- Provide a general summary in the Title above -->

### Expected Behavior
Plugin should work well in Homebridge 1.3+
<!-- If you're describing a bug, tell us what should happen -->
<!-- If you're suggesting a change/improvement, tell us how it should work -->

### Current Behavior
Plugin is non-responsive when controlling some TP-Link devices (HS300 outlets in my case)
This also manifests in the Home app, certain plugs shows as "No Response" (the ones that have devices plugged in)
<!-- If describing a bug, tell us what happens instead of the expected behavior -->
<!-- If suggesting a change/improvement, explain the difference from current behavior -->

### Steps to Reproduce (for bugs)
Homebridge 1.3+ started producing these warnings, but responsiveness was already an issue before.
<!-- Please add a series of steps to reproduce the problem. -->

### Versions
<!-- Please run commands and include versions below. -->
- **Node**:       `10..21.0`
- **Homebridge**: `1.3.1`
- **OS**:  Raspbian 10 on RPi 4 (32-bit)       <!-- The version and architecture of your operating system -->

### Configuration
<!-- Please include the TplinkSmarthome platform section of your config.json file.
Paste between the the two ``` lines below.
-->
```json
        {
            "name": "TplinkSmarthome",
            "platform": "TplinkSmarthome"
        }
```

### Homebridge Log / Command Output
<!-- Paste relevant output between the two ``` lines below
  - Remove any sensitive information, passwords, etc.
  - If output is long:
    - Please extract only the relevant portions if possible (remove other plugin's output, etc)
    - Consider creating a gist, etc
  - However, please include the beginning of the log where the homebridge initialization happens if possible
-->
```
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'On' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'Outlet In Use' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'Amperes' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'Total Consumption' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'Apparent Power' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'Volts' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
[2/26/2021, 7:56:41 AM] [homebridge-tplink-smarthome] This plugin slows down Homebridge. The read handler for the characteristic 'Consumption' didn't respond at all!. Please check that you properly call the callback! See https://git.io/JtMGR for more info.
```
