The study, released on Friday by Parallel Ltd, a UK-based network and internet management company, found that high street banks had the worst availability, page size and download times compared to other financial organisations included in the study.
The findings showed that high street banks were unavailable for twice as long as building societies or internet banks. The average time that sites were unavailable was 108 minutes per month, equating to 21 hours per year.
Download time was another major issue for high street banks. Only 15% of the leading retail banks surveyed had a homepage that would download in 8 seconds or less, which is the recommended maximum time to ensure a good customer experience. On average, home users had to wait more than 18 seconds for the homepage to download, with one in ten waiting more than 30 seconds.
Page size was also a major hindrance for on-line customers, with 75% of banking sites containing web pages that exceed the recommended 40kB limit. The largest page size recorded was 106kB.
Tim Moore, director at Parallel, says the leading banks need to address the issue of file size urgently to alleviate customer frustrations:
"With most internet banking customers still connecting via a dial-up modem, it is vital that banks start to reduce the size of their homepages. Availability is crucial as more and more customers rely on the internet as the main channel of communication with their banks. The leading banks have a responsibility to provide the best service available which simply isn't happening at the moment."