Quartus II 10.0 SP1 to 10.1 - Timing Worse?

I wanted to confirm that Quartus 10.1 does NOT have any conscious reduction in timing closure effort. Any compile time savings you are seeing could be due to your assignment issue (if Quartus thinks timing is easier, it can speed up your compile time significantly). Every release also has various improvements to the compile times that do not degrade timing. Of course, each design is different so there can always be something degrading specific to your design's topology.

In 10.1 and beyond, there is also a new feature where Quartus gives you more information on your failing timing paths (you can access it from TimeQuest by asking for "Report Timing Closure Recommendations"). You can find more details in the Quartus handbook at http://www.altera.com/literature/hb/qts/qts_qii52005.pdf