I think it has something to do with your internet connection.

Sometimes you can't do anything since it could be the server, but most of the time it's because of your internet connection.

It happens when your connection isn't good enough and some packages cannot be send correctly (Loss) or some can't be processed that fast at the same time so they "embottle" until they get processed (Choke).

Loss : Client side packet drops or network packet drops (Basically loss of packets while transferring data)
This happens if you have a shitty connection. All you can do is adjust your cl_cmdrate and cl_updaterate to correct this. Use tracert to see if you are getting any RTOs

Choke : Server side packet loss. This happens if the server is of low quality. You can't do anything to correct this. Maybe rage on the server admin XD