Well, here I am again, with this sheet that takes forever to calculate. I'm still experimenting, but with no success.
The code 
Range("F7", "DN71").Formula = "=SUMIF(Info1!$K$3:$K$43691,Summary!$A7&Summary!F$1,Info1!$I$3:$I$43691)+SUMIF(Info2!$K$3:$K$65536,Summary!$A7&Summary!F$1,info2!$I$3:$I$65536)"
I got , from mewingkitty, still puts the formula in the cells, and I think it still takes too much time to calculate.
And the other formula still jams up at cell row 100.
Thanks for your help.
Xrull

And I haven't cross posted it again.