Try setting first_iter_pres_fac to a value > 0

[vaughnbetz]

We might get faster router convergence if the first router iteration paid some attention to routing congestion (both the cost of wiring and any congestion caused by earlier nets).

Proposed Behaviour

Try setting this to 1 (instead of the default 0) and seeing if QoR is unchanged and router time drops (even a little). For the best impact, we should use the criticalities that come from the placer, rather than setting everything to timing-critical, so that code should also be examined.

Current Behaviour

Defaults to 0. Also, we may set all connections to critical in the first iteration (which we'd have to stop doing to have much effect).

[vaughnbetz]

Another possible optimization: don't timing analyze after every router iteration.

[vaughnbetz]

Possibly tuning experiment for you Nathan, at some point.