It depends on what you are computing. In some cases it will be as fast as the insecure version (not counting encryption/decryption time). On the other hand, r

It depends on what you are computing. In some cases it will be as fast as the insecure version (not counting encryption/decryption time). On the other hand, random access will have to be simulated by a linear scan over an array, which is asymptotically slower. Complex control flow e.g. deeply nested loops with input-dependent side effects can cause the overhead to balloon.