Without an accelerator a Lisa only runs at 5mhz vs. a Mac Plus' 8mhz. While there are certain elements of the Lisa hardware that compensate for the clock difference somewhat a Lisa running Macworks would have been a real slug even by 1987-ish standards.

(Granted it's comparing apples to oranges, but I doubt *any* IBM PS/2, with the possible exception of the 8086 based Model 30, would benchmark slower than a Lisa on abstract computational tasks.)