Lattice Radiant: Why Fmax is reduced after encrypting a source file using IEEE-1735 standard?
This is not uncommon when using encrypted files. Commonly, when source files are encrypted, the same result (or better) cannot be expected from design tools (Lattice tools or any other tools in the EDA industry). When modules/files are encrypted, we are more limited in our optimization options across the boundaries of the encrypted modules. Thus, there will possibly be differences in optimization results between designs with no encryption and designs with encryption. The encrypted modules produce an optimization boundary that cannot be crossed whereas an unencrypted design can be optimized like a flat design with no optimization.