The results seem to be much worse. It seems like it is struggling with so many things identified as clocks. I'd try to change one at a time and increase it gradually.
I just tried on one of my projects that has one clock and supposed to be running at 60 MHz. With that set, it says max is 75.307(MHz). Setting it to 80 MHz, it improves to 80.3 MHz. Setting to 85 MHz. it tops out at 82.085 MHz.
So, it does change the effort in response to the constraints. But the routing strategy setting also matters. Timing change is the most obvious when timing is set as a criteria.
Those numbers are with no operating conditions set at all. With target of 100 MHz I get the following results: I5 and C6 Fast - ~86 MHz, I5 and C6 Slow - ~64 MHz.
In any case, placing and routing is an NP-complete problem, so the tools are doing the best they can given the time constraints. Grownup tools can do a lot of random attempts and pick the best one. This does not seem to have anything like that.