how many fields in the table? Can any be omitted?
Are you matching on more than one field?
are you importing a .fmp12 file or something else?
are the indexes of both the source and target indexed?
importing from a client to a server is very slow for update/imports, as it has to pull the index down to the client, match it, then send the data back for each record in the source.
matching on more than one field also causes performance loss.
matching against a non-indexed key also causes performance loss.
If you are still concerned about crashing, you might want to check out a transactional sync between the two files. FMEasySync is free and would easily be adaptable to this purpose, and would allow for all actions to run on the server in smaller chunks of records rather than an entire file at a time.
It sounds like you plan to do this regularly - perhaps every day - if I understand correctly?
FM will deal happily with large numbers of records without crashing - provided you have designed your system reasonably well. Filemaker is robust technology and FMS13 is stable and reliable.
As you have noticed it is slow to import records if you ask FM to work things out for each record as it is imported.
However - it is very much faster if you import onto a layout based on an isolated Table Occurance - so that there is no opportunity for FM to assess any contextual data - and if you also don't check the do look ups etc on import.
Once you have your original data and the new data all in the same system on your server you may find you are better off undertaking the update between two tables within the same system rather than trying to do an update whilst importing.
Anything run on the server - using perform script on server or a scheduled script will be many times faster than if run from client to server - but be aware that writing effective server side scripts may require a little experience to make them work as you would expect.
Good luck, Nick
There are 12 field in the table and this is .fmp12 file and matching only one field.