quartus_fit out of memory

And note that 32-bit XP only uses 2G natively, even if you have more memory in the system. There is some option to get it up to 3Gb, called /3G, I think.

I imagine you are right on the edge. Also note that the router effort multiplier does not get better timing on most designs. Only if it's hard to route and critical paths are forced to sub-optimal nets might it make a difference. For the most part I never use that option for timing closure. (On the flip-side, it doesn't hurt compile time much, so it generally doesn't hurt.)

Look at the peak memory use in your .flow.rpt. If you're right on the edge, I'd upgrade now. Who knows what other minor tweak starts pushing into out of memory errrors.