Vim's autocomplete is excruciatingly slow

Question

Most of the time the autocomplete feature in Vim works nicely for me, but sometimes it seems to be scanning files which the current file references, and then it becomes painfull

Answer 1

Had a very similar problem since upgrading to Vim 7.3 (from 7.2): I was using the (excellent) ACP plugin and in longer source files (C-files, 1700 LOC), the popup took ages to jump through the suggestions when I was editing near the bottom of the file.

Using the PerformanceValidator (from Softwareverify), I found out that some fold methods were called again and again and lead to very high processor load and slow completion.

My workaround was to set the foldmethod (fdm) to manual. And this solved it...