Steam Internet Connection Speed
Check that you have your Internet Connection Speed properly set to match your internet connection type. You can find it in Steam's File > Settings > Download > Internet Connection Speed.
If you are sharing an internet connection or you suspect that your router is limiting your connection speed, try setting it to the next slower setting.
In-game Rate
Most connections work well with the default rate, cl_updaterate, and cl_cmdrate settings. Most servers prevent changing your in-game rate settings.
Default Settings:
- rate 10000
- cl_updaterate 20
- cl_cmdrate 30