[VM] Weird performance issue with a VM folder

[Daniel Barrett]

I have a VM mail folder with a mysterious performance problem. When
visited with vm-visit-folder, it loads very slowly. For 400 messages
(28MB), it takes about 6 seconds to load. All my other mail folders,
even much larger ones, load instantly (maybe 0.1 seconds).

I was able to fix it by removing all of the "X-VM-..." headers in the
file and letting VM load and save the folder, writing new headers. But
I am curious about *which* headers caused this performance
problem. I'd like to track it down to report a bug.

The old headers at the top of the file were:

X-VM-v5-Data: ([nil nil nil nil nil nil nil nil t nil nil nil nil nil nil nil]
        ["17232" "Friday" "15" "February" "2013" "11:38:17" "-0800" "Name 
Lastname" "address@hidden" nil "317" "8th Grade student/parent night XXHS" 
"^From:" nil nil "2" nil "8th Grade student/parent night XXHS" (number " " mark 
"  B  Name Lastname     Feb 15  317/17232 " thread-indent "\"8th Grade 
student/parent night XXHS\"\n") nil nil nil nil nil nil nil]
        nil)
X-VM-Summary-Format: "%n %*%a %-17.17F %-3.3m %2d %4l/%-5c %I\"%s\"\n"
X-VM-Labels: nil
X-VM-VHeader: ("Resent-" "From:" "Sender:" "To:" "Newsgroups:" "Apparently-To:" 
"Cc:" "Subject:" "Date:") nil
X-VM-Last-Modified: (21629 51968 231600 190000)
X-VM-IMAP-Retrieved: nil
X-VM-POP-Retrieved: nil
X-VM-Bookmark: 430

The new, good headers became:

X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil]
        ["17232" "Friday" "15" "February" "2013" "11:38:17" "-0800" "Name 
Lastname" "address@hidden" nil "317" "8th Grade student/parent night XXHS" 
"^From:" nil nil "2" nil nil (number " " mark "     Name Lastname     Feb 15  
317/17232 " thread-indent "\"8th Grade student/parent night XXHS\"\n") nil nil 
nil nil nil nil nil]
        nil)
X-VM-Summary-Format: "%n %*%a %-17.17F %-3.3m %2d %4l/%-5c %I\"%s\"\n"
X-VM-Labels: nil
X-VM-VHeader: ("Resent-" "From:" "Sender:" "To:" "Newsgroups:" "Apparently-To:" 
"Cc:" "Subject:" "Date:") nil
X-VM-Last-Modified: (21639 20941 92687 525000)
X-VM-IMAP-Retrieved: nil
X-VM-POP-Retrieved: nil
X-VM-Bookmark: 235

Any clues?
Thanks.

--
Dan Barrett
address@hidden