The average lapse between first visiting a shopping site and buying a product is 34 hours 19 minutes, up 80 percent on 2005 when the average delay was 19 hours 11 minutes.
Security firm ScanAlert analysed 2.6 million online sales across 470 shopping sites over a two-year period to produce the report.
"It is a bit of a paradox for retailers. While faster internet access allows customers to complete an order quickly, it also enables them to jump rapidly from site to site," said report author Nigel Ravenhill.
"Combine that with the increasing popularity of shopping search engines, and you have the ideal environment for increased digital window shopping."
The biggest increase was in online shoppers who take more than three days to make a decision.
This means that online retailers should take a longer-term view about the return on investment of their pay-per-click advertising, according to Ravenhill.
- ScanAlert Report: Digital Window Shopping: the Long Delay Before Buying