Drastic difference in Fmax on Cyclone and Stratix

[Altera_Forum]

Hi, 

 I am trying to replicate a multiported RAM design on Cyclone IV which was done by the author using Stratix III . When I compare the Fmax of the designs there is a drastic reduction. The design that had a Fmax at around 370MHz on Stratix has a Fmax of 127MHz!! Why is there such a difference??  The difference in Fmax can also be seen in this document which compares performance of NiosII benchmarks - http://www.altera.com/literature/ds/ds_nios2_perf.pdf  If anyone knows the reason for this kindly let me know.  Thanks.

[Altera_Forum]

Stratix is the high end FPGA family, they are a lot faster than the Cyclones, and cost also a lot more.

[Altera_Forum]

If you look at the Altera Web site you will see that Cyclone IV has speed grades -7 and -8 but Stratix has -3 and -4. The smaller the value the quicker the device.