Fast Models: Best way to model ROMPatch like feature


I am looking for a good way to model a ROMPatch-like function on pvbus. This implementation should monitor the bus for return the data from its own registers if the address matches (instead of returning from the end slave device, say a RAMDevice). Otherwise, it will let the transaction through to the intended slave.

From the documents, it seems that the best way to achieve this is to have a piece of bus fabric (a slave device) that intercepts the all transaction. It will re-issue a identical transaction to the intended slave it the matching fails. Otherwise, it will return the "patch" value from its own register to the original master. This, however, will significantly impacts the simulation performance.

Is there another way to achieve this without significantly compromising the performance? Any ideas will be great! Thanks.