Electrical box grounding or supply issue?

I’ve replaced an old screw in fuse panel with a new 100 amp panel and breakers. When using a corded circular saw plugged into one of the new circuits (14g wire), all the lights in the house (on separate circuits) would dim. Is this caused by a bad ground, bad feeder wire from meter to box, too small of a feeder wire gauge or something else? How could I fix? Thanks.