optimization_level = 3, which is the layout method used by default?
You can pass a
layout_method=... arg to set this yourself. It currently accepts
(There is a also an option for
routing_method=... which accepts
The difference between the various levels (0,1,2,3) is then what parameters these passes run with. At higher level, they run with more time-consuming parameters which will probably yield better results. For example the number of trials is higher, or the lookahead window is larger.