Networking is a big impact in performance regardless what you are using. TCP and UDP are quite similar in performance in relation to the timeframe you are monitoring. Human reaction time is supposed to be not that huge and even a really skilled secretary just is able to hit 150 buttons per second at max. This are 7 ms while a game running on 100 FPS has round about 10 ms update loop. This is quite insane!
Assuming you eliminate all outer circumstances like a bad Wifi connection, complicated Network infrastructure and your wife/man is not downloading an ESO update of 100 GB (why Zenimax, why??) on the same time, you should achieve a good response time anywys regardless if you're using UDP or TCP.
Why is TCP considrred to be slow? Because it has these streaming character that messages are like binary streams send in the same order they are placed onto the socket buffer from an application. So you ensure that everything is send and in the right order. UDP is different, it is just fire-and-forget approach for broadcasting messages in the whole network to find the game server your friend hosted in your local LAN-party. This lets assuem people that TCP is slower (which is true) but not significant slower perhaps.
However, TCP has the benefit to be safer in case of recognizing connection loss but you could acieve this also with UP by simply tracking the timestamp of packages that arrive at your target. If packages are not received for certain time, assume a connection loss.
However, in the end the data matters and how you are handling them. Sending 100 GB of data in a synchronous way has a significant lower performane than using a thread-pool/ IOCP on Windows and if you block the thread to process the message for several milliseconds before starting a new receive call will also cause a performance loss