16-bit CRC Vs 32-bit CRC

That may well be. The CRC is basically a self feeded shift register of the named length. So yes, a CRC16 reaches a higher frequency than a 32bit shift register. On the other hand there are faster implementations than the shift register approach. This operates with tables. I've worked with a CRC16 that was using a 256byte table and operated on a word (16bit) at once. It was run on a PC as well as on a controller, years before FPGAs came out. So if speed is an issue, have a look at the table based CRC implementation. It is available for the CRC16 as well as for the CRC32.