I ran a few tests comparing my iPad 2 on 7.1, my iPad mini and iPad mini retina both on 8.1.1. Previously, with 8.1, the iPad mini retina had been loading pages at about the same speed as the iPad 2 running 7.1. Now, with the iPad mini retina on 8.1.1, its about 20% faster than the iPad 2. It used to be a night and day difference. These are just eyeball numbers, no stop-watch or anything. I use CNET as my test page and count when all the graphics have settled as the stop point. I clear the cache before each test so the page has to load entirely.
Then I compared the iPad 2 to the iPad mini (non retina). Remember, these two machines have basically the same memory and processor. The iPad mini on 8.1.1 takes about 2x the time to load a page as the iPad 2 on 7.1. So I conclude that iOS 8.1 slowed Safari by somewhat more than 2x, followed by an about 20% improvement with 8.1.1, speeding it up to just 2x slower than 7.1 on page loads.
Links on Amazon still take presses under 8.1.1, not just taps, to work. I tried this on multiple iPad mini's at the Apple store during the 8.1 revision. All were requiring presses, not taps, on links on the Amazon website. I haven't been back since the 8.1.1 upgrade, but wouldn't expect to see any differences.
I only had Google links hang on me once under 8.1, and never yet under 8.1.1, though this doesn't mean it won't happen.
Other issues I ran into with 8.1 haven't been thoroughly checked out since the 8.1.1 update. One was interesting. With GPS geofence running, my iPad mini retina sometimes wouldn't activate the keyboard to enable password entry when turned on with the smart cover; the keyboard would appear on the screen but wouldn't take any input. This happened while I was sitting outside the local Apple store, and nowhere else, hence the link to the geofence. I could get the keyboard back up and running by toggling the power on/off switch.
I've got about 280 apps on each iPad, and have the memory 80-90% full on all of them. I don't use push, but have GPS, LTE, and bluetooth up and running. My home WIFI runs about about 30Mbps download and 25Mbps upload as tested by Speediest on the iPads.