Content originally posted in LPCWare by nxp21346 on Wed Feb 06 12:13:46 MST 2013
The synchronous bus used by the SDRAM is typically more efficient than the asynchronous bus used by SRAM. However, you have specified using a 10 ns SRAM which is very quick so it may be comparable. Also, SDRAM operation at 200 MHz is not supported on the LPC43xx (the maximum is 120 MHz).
-Dave @ NXP