## 15 Fast loading of frozen state ¶

Some bigger `m4` applications may be built over a common base containing hundreds of definitions and other costly initializations. Usually, the common base is kept in one or more declarative files, which files are listed on each `m4` invocation prior to the user’s input file, or else each input file uses `include`.

Reading the common base of a big application, over and over again, may be time consuming. GNU `m4` offers some machinery to speed up the start of an application using lengthy common bases.