How much violation is ok?

To give more details of my project:

There are 100 and 200 MHz domains in my design and violations are obviously in 200 MHz domain. I have tried DSE - but these violations are hard to close. The violations are inside DDR2 controller of Altera (it is encrypted, so no way I can try to fix them). To make matters worse, the device utilization is a whopping 90%.

Also, does it make sense to run DSE on a machine with 4GB RAM and i5 core processor on Windows 7 - I see it hang after 3 to 4 iterations.