I'm doing a Modelsim simulation with the Arria 10 EMIF DDR4. Using the IP generated testbench. The abstract PHY option is relative fast, using the DDR4 memory model is painfully slow.

Skip calibration mode will still run the calibration in ideal case. The details as below:

In Skip Calibration mode, the calibration processor assumes an ideal hardware environment, where PVT variations, board delays, and trace skews are all zero. Instead of running the actual calibration routine, the calibration processor calculates the expected arrival time of read data based on the memory latency values that you provide, thus reducing much simulation processing.

Thus, you will still see the clock running and calibration pass signal assert.