Get latest timestamp of MF4

[geo4711]

Hi,
I have many MF4 files with bus logging for several CANs. I'm looking for a method to quickly find out start and end time of the measurement. Start of measurement is contained in the MF4 header. But I couldn't find a quick way to retreive the timestamp of the latest event.
Iterating over all busses (mdf.select(...)) to get the latest timestamp per channel takes a long time for large files (e. g. files with 5 to 10 GB). I already saw the parameter record_offset for mdf.select() and tried to set it to -1 (like common slicing in python). But this did not return the latest sample/timestamp.
I'm wondering how CANoe retreives this information within some seconds.
Does anybody have an idea for a quick method with asammdf?

Thanks in advance for any help!