How to suspend VIM history?

You don't need to suspend Vim history. The actual data forms a tree, and you can retrieve it with the undotree() function. There are, of course, a number of plugins that turn that into something more user-friendly, f.i. gundo, mundo, and undotree. If you also enable undo persistence (cf. :h undo-persistence) you can easily navigate through the entire change history of a file.