What iPad Models are you using and how is the object spy performance?

We are starting iOS testing and have used an iPad 4, iPad Air and iPad Mini 1 so far. We see very bad performance with the iPad 4, the object spy takes about 15 seconds to load everytime. The Air only takes a couple seconds and the Mini only takes about 5 seconds. The mini has a slower processor so we're a bit surprised it's peforming better than the iPad 4. We have tried two iPad 4 devices, so it's not something off with the device. What are other people's experience?

Thanks,

Adam