Internet Banking painfully slow since upgrading to iOS 8.3

Hi there, since upgrading to iOS 8.3, I have noticed that the Internet banking for one of the banks that I bank with has become painfully slow. I work for this bank and have been made aware that over 50 customers have complained of a similar experience. Common factors between these customers is that all of them are using Apple products with most of them on the Spark network. Has anyone out there faced similar problems?