mouse lag

ok i quit for about a year and came back yesterday. then when i log on to the game, it just lags, especially in game. its also lags in the lobby, storage, black market, and store. my computer is a windows vista compaq from 2007 with an AMD athlon(tm) 7550 dual core processor with 2.50 Ghz processor. my mouse is a wired compaq mouse that comes with the set and a wireless swiss gear mouse. idk my DPI cause idk where to find it. plz help i really want to play and if i could get the game working again, i'm getting 20000 ZP.