Once inside the Server and once in the cockpit on the tarmac, press "S" key and you can see your ping value.
This is the stock key to show the list of players and statistics, their pings (in miliseconds) and points. If you can't see anything, you'll have to go into the "Controls" section and configure the key for "Online Rating" in the "MISC" area.
This is the real ping you have against the Server in that moment. Sometimes, a high ping can be caused not by yourself but simply if the Server has not a good connection, there too many people connected, or just if the Server is on the other side of the World !
PD: and do not forget , when going on line, to close any other program in your PC which can be using part of your Internet connection like P2P programs, etc. It is advisable to leave all our bandwith for IL-2 and related programs as Teamspeak, HL, etc.
EDIT:
If you want to know who is causing the message "Cheating has been detected!" to show, go to the game's folder, then subfolder "i18n", and open with Notepad the file "netmessages.properties".
Look at the beginning of the file for the lines:
user_cheating1 cheating has been detected
user_cheating2 cheating has been detected
user_cheating3 cheating has been detected
(I am not sure about the exact build of these phrases in the stock game because I changed them long ago)
and write them as :
user_cheating1 {0} is causing lag!
user_cheating2 {0} is causing lag again!
user_cheating3 {0} is causing lag 3 times!
save the file, and you'be able to see the name of the pilot who is causing lag.
Of course keep a safe copy of the stock file "netmessages.properties" before modifying it in case of any problem.