Depends on your model.
If you aren't using any power electronics blocks (inverters, transistors, etc.) and your frequencies are constant, you can take advantage of Phasor simulation mode in Specialized Technology. This will be much faster than discrete or continuous simulation modes.
Right now, the Simscape Components library only has continuous and discrete modes, which are configurable by enabling the "Use local solver" option in the Solver Configuration block.
If you do have power electronic devices, then you cannot use Phasor simulation. In this case, the simulation speed should be comparable between the two block libraries.