Wikipedia lists the Ripon IIC as 111 mph top speed, which is still faster than the Po-2 or storch, thoughcertainly slower than the Stringbag. So maby the slowest torpedo bomber. It might have been the slowest when carrying a torpedo, I doubt it did more than 100 mph fully loaded and if slower than 95 mph, we have a winner!
Though I don't know the stats for Finland's Ripon IIF.