Lahti finished in tenth place in the time 15.10,24, which is 52 hundredths better than her previous personal best.
The competition was won by the Kenyan star Hellen Obiri who set the season best with a time of 14.26,38.
Second was Fantu Worku, Ethiopia and third Margaret Chelimo Kipkemboi.
Norwegian Karoline Bjerkeli Grövdal was eight and two places behind came Lahti.