OK Bob,

Using your beginsWith2: I was able to get the time on a 4+Mb file down 
from 7125 to 4186 msec (a 41% improvement).

|file1 file2 aFileDirectory aFileList line lf cr|

MessageTally spyOn:
[
lf := Character lf.
cr := Character cr.
aFileDirectory := FileDirectory on: '/home/ned/Squeak/3.2/mailtest'.
aFileList := aFileDirectory fileNames.
aFileList do:
  [ :aFile |
  file1 := StandardFileStream new.
  file1 open: aFileDirectory fullName, '/', aFile forWrite: false.
  file1 := ReadStream on: file1 contentsOfEntireFile.
  file1 reset.
  file2 := StandardFileStream new.
  file2 open: aFileDirectory fullName, '/', aFile, '.txt' forWrite: 
true.
  [file1 atEnd] whileFalse:
  [ line := file1 upTo:  lf.
	line size >= 4 ifTrue: [ | firstChar |
	firstChar := line at: 1.
	(firstChar = $f or: [ firstChar = $F ]) ifTrue:
	[ (line beginsWith2: 'from') ifTrue:
   		[(line includes: $@) ifTrue: [ file2 nextPut: Character space 
]]]].
  file2 nextPutAll: line; nextPut: cr] .
  file2 close.]].

The MessageTally on this looks like:
 - 209 tallies, 4186 msec.

**Tree**
45.5% {1905ms} ReadStream>>upTo:
  |25.4% {1063ms} String(SequenceableCollection)>>copyFrom:to:
  |  |14.4% {603ms} primitives
  |  |11.0% {460ms} String(Object)>>species
  |12.0% {502ms} primitives
  |8.1% {339ms} String>>indexOf:startingAt:ifAbsent:
20.6% {862ms} StandardFileStream>>nextPutAll:
20.1% {841ms} StandardFileStream>>nextPut:
9.6% {402ms} primitives
 
**Leaves**
20.6% {862ms} StandardFileStream>>nextPutAll:
20.1% {841ms} StandardFileStream>>nextPut:
14.4% {603ms} String(SequenceableCollection)>>copyFrom:to:
12.0% {502ms} ReadStream>>upTo:
11.0% {460ms} String(Object)>>species
9.6% {402ms} UndefinedObject>>DoIt
8.1% {339ms} String>>indexOf:startingAt:ifAbsent:

**Memory**
	old			+0 bytes
	young		+4,959,044 bytes
	used		+4,959,044 bytes
	free		-4,959,044 bytes

**GCs**
	full			0 totalling 0ms (0.0% uptime)
	incr		54 totalling 202ms (5.0% uptime), avg 4.0ms
	tenures		0
	root table	0 overflows

-- 
Ned Konz
http://bike-nomad.com
GPG key ID: BEEA7EFE