Sounds like same bug a few of us are having. Are you in Casual mode too?
http://sinisterdesign.net/forum/index.php?topic=1577
http://sinisterdesign.net/forum/index.php?topic=1573.0
I also noticed that it seemed to get worse after a few battles, and each time would cause the game to lag more during startup while that character was in the active team. After a few battles it actually got to the point where it crashed the game if they were chosen. So without seeing code obviously it sounds like something that is happening at either the battle pre phase, or battle post phase? crash and slowdown is probably not directly related, but is a side effect of parsing the duplicated items/skills.
http://sinisterdesign.net/forum/index.php?topic=1577
http://sinisterdesign.net/forum/index.php?topic=1573.0
I also noticed that it seemed to get worse after a few battles, and each time would cause the game to lag more during startup while that character was in the active team. After a few battles it actually got to the point where it crashed the game if they were chosen. So without seeing code obviously it sounds like something that is happening at either the battle pre phase, or battle post phase? crash and slowdown is probably not directly related, but is a side effect of parsing the duplicated items/skills.