As described in Import/convert 600 TextExpander macros for KM, Keyboard Maestro Engine can handle more or less any number of text expansion macros, but each simple typed string macro occupies about 200 bytes in the monolithic macro save file. This makes 200K per thousand expansions. Depending on the speed of your Mac and your harddisk, the editor may start to slow down if you have many thousands of such expansions.