I've found the frosted glass blur slows safari down significantly. There is an option to disable the frosted glass look in settings > general > accessibility >

I've found the frosted glass blur slows safari down significantly. There is an option to disable the frosted glass look in settings > general > accessibility > increase contrast > reduce transparency. My iPad Mini 2 runs much faster with this enabled. Edit: This only applies to the 4th generation iPad and up. Apparently the frosted glass look was never enabled for the third gen iPad.