I once had the bug that I couldn't perform any actions at all in the middle of the fight. No attack, no guard, nothing. I needed to go into passive mode and back to active mode to be able to attack again.
I had this issue one time in a party, fortunately none of us got killed. It happened to my ls buddy conjurer when it happened to me. What I did was go to passive mode, once back in active I was able to attack. I don't know what is going on with that. Apparently quite a few people are having this issue.
My game is crashing as well after the update has been implemented. I've never crashed before. I've had server errors, but that's it. I've only had one server error, while my game has crashed several times. Went to do leves, failed 2 out of 3 thanks to the game crashing. First time I was on the last mob I needed to kill. Second time immediately after I killed the last one. 40 minutes later I received some gil and a message that more or less said "You receive gil for a leave you didn't collect your rewards on". That had to be from the quest that I killed the last creature right before I d/c.
I have noticed that I am running slower now, though I didn't notice it right away, until my roommate mentioned how slow he was moving.
Toward the end of my playing last night, my game started getting really laggy. I don't know why, wind wasn't blowing or anything. I wasn't receiving tons of information, to account for the lag.
I also have had some issues with the targeting system not always working properly. But, I know that this is an issue that already knew about due to the update. I don't always wait for my character to target the next mob, it tends to take too long to target the next mob. Especially if you have to wait for the mob to attack you until it locks onto the mob. I just hit tab or use my mouse to target the mob. The targeting is working better imo.