Update: Someone in Reddit has posted a solution that seems to works. However, this method involves a lot more and can possibly break the game. Take it at your own risk.
https://www.reddit.com/r/PSO2/comments/gsn90o/workaround_fix_unbearable_lobby_lag
Original Post: So I was playing around with Nvidia control panel because the game is blurry even in the highest setting, but then discovered this: In the Nvidia control panel, if you set Antialiasing - Mode to Override any application setting, and set Anisotropic filtering and Antialiasing filtering to a number, the game will no longer stutter freeze in the lobby. There are still lags, but on my end, the game no longer freezes up the computer entirely for 0.5-1s anymore.
Well, my method might not work, but at least improved the graphic, as the game does not even have AA option... lol.