This was investigated in 2013 by Garson O’Toole (aka ‘Quote Investigator’), who traced the joke back to a 1958 column by Sid Ziff, then sports editor of the Los Angeles Mirror News:
[Bill] Miller, who contributes now and again to Inside Track, once wrote a book titled “To You I Tell It.” It received mixed reviews. One critic said: “It is not a book to be lightly thrown aside. It should be thrown with great force…”
Sid Ziff (18 December 1958). ‘The Inside Track’. Mirror News. Los Angeles, California. Via quoteinvestigator.com.
O’Toole was unable to identify the “critic”, and there is always the possibility that the joke was original to Ziff and attributed to an anonymous critic because it was funnier that way.
Jokes about throwing books long pre-date Ziff’s, and O’Toole found a couple of examples from Dorothy Parker:
That gifted entertainer, the Countess of Oxford and Asquith, author of “The Autobiography of Margot Asquith” (four volumes, neatly boxed, suitable for throwing purposes), reverts to tripe in a new book deftly entitled “Lay Sermons.”
Dorothy Parker, writing as ‘Constant Reader’ (22 October 1927). ‘Recent Books’. The New Yorker, p. 98. Via quoteinvestigator.com.
I’m much better now, in fact, than I was when we started. I wish you could have heard that pretty crash “Beauty and the Beast” made when, with one sweeping, liquid gesture, I tossed it out of my twelfth-story window.
Dorothy Parker, writing as ‘Constant Reader’ (14 April 1928). ‘Reading and Writing: Mrs. Norris and the Beast’. The New Yorker, p. 98. Via quoteinvestigator.com.
Perhaps it was memories of these New Yorker reviews that caused people to begin attributing Ziff’s joke to Parker, starting in the 1960s.