With most games the problems of lag are not player related (unless your hardware is unable to run them) but the server hardware and way those servers are connected to the internet .
For example a certain space based game used to have massive lag (it could be 10 minutes for a skill to activate) with huge blobs (1000’s of players) fighting ; the answer was to reinforce nodes and finally using the latest hardware on their servers along with making their software more efficient (took several years to implement but they got there). Now they have no problem!