I would recommend you give Phil's ethernet ip driver a go Automation Professionals' EtherNet/IP Communication Suite V2 - #108 by pturmel
He has seen 15x better performance when reading AOI tags directly compared to the IA driver. It's a direct drop in replacement for IAs driver and honours the demo period. What you need to ensure however in your plc programmes, is that all members of the AOIs and udts you're reading are set to at least read external access. You can do this easily if you export to an l5k.