[luki1412]

cl_cmdrate - This command sets the max number of command packets that are sent from your client to the servers each second.

cl_updaterate - This command is used to set the number of packets per second of updates you request from the server.

Its not really a trick when you lower them. Servers can also enforce them via server commands:
sv_mincmdrate sv_maxcmdrate sv_minupdaterate sv_maxupdaterate

If you lower them, you send and receive less data but that also means that your game has to simulate where a player is, more often. Could be missing your shots more due to that.