Actual duration that you see in web console is only measured duration (page load). Actual playback usually takes more time (finding elements on the page, clicking, ...). So transactions can run much longer than reported.
You can find actual playback duration of transaction if you enable DEBUG logging for WPM Business Layer through Log Adjuster (Start -> All Programs -> SolarWinds Orion -> Documentation and Suppport -> Log Adjuster). Once you set "WPM Business Layer" to DEBUG and apply changes, playback statistics will be logged to c:\ProgramData\Solarwinds\Logs\SEUM\SEUM.Performance.log once playback finishes.
File lines have format:
Transaction <Transaction ID> <Transaction Name> (rec: ... agent: <Agent ID>): | measured duration as timespan | playback duration as timespan | measured durations as total seconds | playback duration as total seconds
You are interested in "playback duration" columns. You can import this file for example to Excel with "|" as a separator to get better overview. If you find some transactions that have very long playback durations compared to measured durations, there may be some issue with them that is causing them running too long. It would then need closer investigation what is causing that.