Malwarebytes CEO Marcin Kleczynski explains a bad protection update caused these problems in a post to their forums. A new update has been pushed that resolves these issues. This new protection update causes mbamservice.exe to consume a lot of memory and upwards to 90% of the computer’s CPU. This has caused some computers to crash or become too unstable to use the program. The suggested method to fix these issues are: Turn off web protection by clicking on Settings, then click on the Protection tab, then set the Web Protection to OFF.
Source: https://www.bleepingcomputer.com/news/security/malwarebytes-update-released-to-fix-high-cpu-and-memory-usage-in-mbamservice-exe/