Ethernet MAC

You can't use the c2h checksum together with a tightly coupled data memory. A tightly coupled data memory can only be connected to one master, and the c2h instantiation would require a second master. You can only have one at a time.

From my experience, on my design and in my testing conditions, using the c2h checksum was actually slower than doing the checksum in software on a tightly coupled data memory. But this is strongly application dependant.

Don't forget to compile the software with optimisations! By default in the debug mode there are no optimisations, and the code is really slower.

For the last point, I first profiled the application to see what functions were the most used, and placed them in a tightly coupled instruction memory. For that you first need to add a parameter to the compiler so that it puts each function in a different linker section, and then use a custom linker script to put those sections in the tightly coupled instruction memory. I can try and find out my software project where I did this if you want more details.