Exiting a process cleanly is difficult and expensive. Avoiding race conditions becomes almost impossible with complex software and a clean exit can be quite slow. Waiting on all threads, paging in code and data, and race conditions make it not worthwhile.This should result in lower memory consumption versus the method Chrome is currently using. One issue it should prevent is that under current condition, memory usage doesn't go down when you close a couple of tabs or even a full browser window.
We have been gradually moving towards using TerminateProcess for more process types. Although the majority of the shutdown processes tracked by this bug are in utility processes this change uses TerminateProcess for all process types. We should not need to let destructors run so it should be safe to never use exit() (or to make it opt-in).
Source: MS PowerUser