1. A method for improving physical synthesis of a circuit design, the method comprising: performing an analysis for determining pattern-based scaling factors, wherein the performing of the analysis comprises: combining attribute ranges of different physical attributes of nets to form net patterns, the nets including circuit elements and interconnections; and for each of the net patterns, computing a scaling factor to be included in net routing constraints, wherein the scaling factor is computed based on a relationship between a predicted route property and a post-route property, wherein the scaling factor is applied to a set of nets matching the net pattern during a next phase of placement-based optimizations; analyzing, by a computer system, preliminary routing information of a plurality of nets in the circuit design; identifying critical nets based on statistical distribution of the preliminary routing information of the plurality of nets; assigning the identified critical nets to a set of routing layers; and removing the identified critical nets from the analysis for determining the pattern-based scaling factors; and adjusting the pattern-based scaling factors to provide a snapshot of a current state of a layout of the circuit.