I have the same issues when it comes to the lobby rooms or trying to get a match on rank. It drives me nuts that I thought this would be the best version of Injustice yet we have all these online issues and if you ever try to do a VS game with a friend (Local not online) and have different controls then the default the game changes your buttons every time you return to the character select screen. At least that's an issue i been having which makes playing this with my friends a pain in the ass.
I also have a good videocard which can run this game on the max settings in single player mode plus a brand new 8core AMD CPU (4.3 ghz). The few times I have played online the connection was bad even though i saw the other players speed was good. Kinda annoys me that I have to worry not only about internet lag now but also if someones pc can't run the game (which will lag the game like MK9 on PC) & finally hoping to find a player to play. I have better luck finding a game on MK9 for PC which has empty rooms a lot of the time also and most players besides Mike I see are not in the US.
I tried to play
Mikemetroid after the last patch on pc and i couldn't connect to his game at all. I have to try it again sometime. I thought maybe it was a router issue but i haven't found anything online about forwarding any ports and i don't have this issue with any other of my steam games. I think I am going to end up buying injustice when I get a PS4 and hope their online is not as bad a PC being they were both ported by the same company (High Volatage i think is their name).