Mac Startup slows dramatically when Malwarebytes Premium 3.9.23 "real-time protection" features engaged

After an hour with Apple support, I learned that startup time for my Mac (Mojave 10.14.6) was being slowed down dramatically after the latest update to Malwarebytes Premium v. 3.9.23. With "real-time protection" features Ad Block and Malware Protection engaged in Malwarebytes premium, Startup (from turning on my Mac to reaching the login screen) took up to 4 minutes. After unchecking those features on Malwarebytes before shutting down, startup time returned to normal: under 20 seconds.

Curiously, the same startup slowdown does not occur on my MacBook Pro (High Sierra 10.13.6) with Malwarebytes Premium v. 3.9.23 with the "real-time protection" features engaged. Any clues?