Importing text files very slow in Version 12 in comparison to Version 11

Hello

I have imported exactly the same text files into network versions of V12 and V11 databases and have found V12 imports very slowly.

V12 -  Importing  text files of 1000 refs takes 17 mins to import

V11 -  Importing exactly the same text files of 1000 refs takes 45 seconds to import

Has anybody else had the same problem and if so have they found a fix for this problem?

Thanks

Clarkelz