- Why is my network speed so slow suddenly?

The network speed is not a static variable but it is dynamically adjusted according to the type of applications users are using, the network condition of the websites users are trying to reach and the network utilisation at that time. Speed may also vary depending on the phone you are using, its RAM, the number of applications you have as well as your location. 

You may want to:
- check if other applications are still running in the background and turn them off 
- check that you are not connected to wifi
- try surfing another website to see any difference
- try moving to another location to see any difference
- delete programs you never use
- turn off visual effects and autoplay videos 
- restart your phone 
- clean up / declutter your phone memory and storage