The plugin makes a separate call to CF for every single test method. The Method Timeout setting allows you to specify a maximum amount of time, in seconds, the test runner should wait for a single test method to complete. If a method call does not complete in the time specified, the plugin stops trying and moves on to the next test method. You can use a setting of "0" seconds to specify NO Timeout. The default setting is 30 seconds, which would allow an extremely long-running test.
In addition, the method timeout can be changed by clicking on the dropdown triangle to the right side of the MXUnit view and clicking the "Change Timeout Preference" menu item. From there, enter your desired value.