Just to clarify, "close and reopen" in my case means using the task switcher to kill off the app (whether or not iOS 11 actually does any kind of process termination, I don't know), then opening the app again.That still seems way too long for an iPhone 6, given my iPhone 5s does it significantly faster even on power save mode. Especially the close and reopen times, those shouldn't take several seconds.
I'd suggest doing a clean install of iOS via iTunes on your Mac or PC.
Subsequent opens for Wallet: 2s
Subsequent opens for Maps: <3s
I might do a clean install anyway, thanks for the suggestion : )
What are your times?