I can tell it has been that way at least from when I started to play this game. Heard the same from squadmates as well. The reasons can be multiple, starting from your mood and mental alertness to issues in your Internet connection. The latter is rather about instability than response time so looking at the ping doesn't tell you much unless it's way off. The reasons for Internet instability are multiple as well, a novelty on Netflix, a new meme spread all over, scheduled banking transactions, a change in oil or stock prices, Trump calling "get well soon" to Kim, rain or thunder somewhere along the route, sunspots, you name it...