Check what type of lag you are having...
I guess you should press F11 and check the table at the top right. (in FAF)
in vanilla you can do the same, but need to use console command "ren_shownetworkstats" to display the table, and can type command again to remove the table.
i'd mainly suspect the net lag to be the issue.
If it is not net lag then check ingame FPS with / key on numpad
can check if you have those problems in singleplayer
Edit: ah yea, about the table...
if you see numbers in "behind" column, it usually indicates internet issues
Here is some picture i have found but i used AI to translate from RU to English so it looks weird
"behind" column is usually the most important one