-"Make this field blank or 0, or increase this number to use multiple "
-"threads.\n"
-"On multiprocessor systems, this will improve mapgen speed greatly at the "
-"cost\n"
-"of slightly buggy caves."
+"Empty or 0 value:\n"
+"- Automatic selection. The number of emerge threads will be\n"
+"- 'number of processors - 2', with a lower limit of 1.\n"
+"Any other value:\n"
+"- Specifies the number of emerge threads, with a lower limit of 1.\n"
+"Warning: Increasing the number of emerge threads increases engine mapgen\n"
+"speed, but this may harm game performance by interfering with other\n"
+"processes, especially in singleplayer and/or when running Lua code in\n"
+"'on_generated'.\n"
+"For many users the optimum setting may be '1'."