The main performance hog is the full redraw of the whole morph for every 
single #endEntry send. The morph re-renders all visible lines (see 
NewParagraph >> #displayOn:using:at:).
If the visible lines' were cached on a form (probably one form per line), 
and only the newly added text were drawn during the update, then I think 
the performance would be similar to Cuis's implementation's, but without 
restrictions (text not selectable/editable).

Levente

On Sat, 9 May 2015, Eliot Miranda wrote:

> Hi Juan,
>     I see that your new transcript is indeed much faster but is also not editable.  I wonder if it would be possible to have the best of both worlds and arrange that, when active, the transcript is editable. 
> For example, selecting the TranscriptWIndow could put it into a mode where the transcript's state was imported into a more conventional editable text morph, and then when the window was exited, reverted to
> the standard fast output mode.  As you can infer I like having an editable transcript.  I can do without it, because Squeak's slow transcript is indeed a PITA, but I'm not sure that speed need preclude
> editability.
> 
> On Sat, May 9, 2015 at 10:17 AM, J. Vuletich (mail lists) <juanlists at jvuletich.org> wrote:
>       Hi Folks,
>
>       (below)
>
>       Quoting Ben Coman <btc at openinworld.com>:
>
>             On Sat, May 9, 2015 at 10:35 PM, Eliot Miranda <eliot.miranda at gmail.com>
>             wrote:
> 
> 
>
>                   On Sat, May 9, 2015 at 7:09 AM, Ben Coman <btc at openinworld.com> wrote:
>
>                         From my limited experience bug hunting, calling #changed: from a thread
>                         other than the UI thread is a source of evil.  There are too many
>                         assumptions throughout the system that the UI is single threaded.  Can
>                         anyone advise me that is not a proper belief?
>
>                         Then that implies that a Transcript implementation where #nextPut: direct
>                         calls #changed:
>                         is not appropriate for use with multi-threaded applications.  In Pharo,
>                         #changed: is only called from #stepGlobal, which is called from
>                         doOneCycle:.  (This came about as a last minute bug fix before Pharo 3
>                         release and maybe could use some cleanup.
>
>                         Separating the UI from Transcript into its own viewer might be a good
>                         idea, but actually it would not solve Stef's case since his code would
>                         still be running in the UI thread -- unless the viewer ran in another
>                         thread, which would have its own complexities.
>
>                         I think the point about efficiency is significant. The following
>                         example...
>                              Time millisecondsToRun: [ 1000 timesRepeat:  [ Transcript show: 'x'
>                         ] ]
>                         on Squeak 4.5 --> 12749ms
>                         on Pharo 50029 --> 2ms
>
>                         This better performance helped me a lot trying to understand the high
>                         priority timerEventLoop being able to indiscriminately scatter Transcript
>                         tracing through that code.  I believe its also probably beneficial for
>                         working with externally triggered semaphores and timing sensitive race
>                         conditions.
>
>                         So we have two mutually exclusive cases:
>                         * better interactivity, poorer system performance
>                         * faster system performance, worse interactivity
>
>                         Which of these is broken depends on your viewpoint.
> 
>
>                   Something that runs fast but is incorrect is still incorrect.  The fact
>                   that the transcript doesn't output until a world step is possible is a
>                   bug.  It forces programs that use the transcript to be rewritten in order
>                   to see transcript output.
> 
>
>             As a point of comparison for correctness, for the following...
>
>                 Transcript clear.
>                 [   $a asciiValue to: $z asciiValue do: [ :c |
>               [ 1 to: 9 do: [ :i | Transcript show: c asCharacter printString , i
>             printString , ' ' ] ] forkAt: 40
>             ].
>                 ] forkAt: 41
>
>             Squeak 4.5 gives...
>             $a1 $a2 $a3 $a4 $a5 $a6 $a7 $a8 $a9 $b1 $b2 $b3 $b4 $b5 $b5 $c1 $c2 $c3 $c4
>             $c5 $c6 $c7 $c8 $c9 $d1 $d2 $d3 $d4 $d5 $d6 $d7 $d8 $d9 $d9 $e2 $g2 $h2 $h2
>             $i2 $k2 $k2 $l2 $n2 $n2 $o2 $o2 $r2 $s2 $t2 $u2 $u2 $v2 $x2 $y2 $z2 $z2 $b7
>             $f3 $e3 $e3 $g3 $j3 $h3 $i3 $k3 $k3 $m3 $n3 $p3 $p3 $q3 $o3 $s3 $t3 $t3 $u3
>             $v3 $x3 $y3 $z3 $b8 $f4 $e4 $e4 $g4 $h4 $i4 $k4 $l4 $m4 $m4 $n4 $r4 $q4 $o4
>             $o4 $s4 $w4 $u4 $u4 $v4 $y4 $y4 $z4 $z4 $f5 $j5 $j5 $g5 $i5 $k5 $l5 $l5 $m5
>             $m5 $n5 $q5 $o5 $s5 $s5 $t5 $u5 $u5 $x5 $y5 $z5 $f6 $f6 $h6 $h6 $g6 $g6 $k6
>             $p6 $m6 $r6 $r6 $n6 $o6 $s6 $s6 $w6 $u6 $x6 $x6 $e7 $f7 $j7 $h7 $h7 $i7 $l7
>             $l7 $k7 $m7 $m7 $q7 $n7 $n7 $o7 $t7 $w7 $w7 $u7 $v7 $x7 $z7 $z7 $e8 $e8 $h8
>             $g8 $i8 $i8 $l8 $k8 $k8 $m8 $q8 $n8 $n8 $s8 $t8 $w8 $y8 $y8 $u8 $x8 $z8 $f9
>             $f9 $e9 $h9 $h9 $g9 $p9 $p9 $k9 $r9 $r9 $m9 $n9 $n9 $o9 $t9 $t9 $w9 $v9 $u9
>             $u9 $z9 $x9
>
>             Pharo 50041 gives...
>             $a1 $a2 $a3 $a4 $a5 $a6 $a7 $a8 $a9 $b1 $b2 $b3 $b4 $b5 $b6 $b7 $b8 $b9 $c1
>             $c2 $c3 $c4 $c5 $c6 $c7 $c8 $c9 $d1 $d2 $d3 $d4 $d5 $d6 $d7 $d8 $d9 $e1 $e2
>             $e3 $e4 $e5 $e6 $e7 $e8 $e9 $f1 $f2 $f3 $f4 $f5 $f6 $f7 $f8 $f9 $g1 $g2 $g3
>             $g4 $g5 $g6 $g7 $g8 $g9 $h1 $h2 $h3 $h4 $h5 $h6 $h7 $h8 $h9 $i1 $i2 $i3 $i4
>             $i5 $i6 $i7 $i8 $i9 $j1 $j2 $j3 $j4 $j5 $j6 $j7 $j8 $j9 $k1 $k2 $k3 $k4 $k5
>             $k6 $k7 $k8 $k9 $l1 $l2 $l3 $l4 $l5 $l6 $l7 $l8 $l9 $m1 $m2 $m3 $m4 $m5 $m6
>             $m7 $m8 $m9 $n1 $n2 $n3 $n4 $n5 $n6 $n7 $n8 $n9 $o1 $o2 $o3 $o4 $o5 $o6 $o7
>             $o8 $o9 $p1 $p2 $p3 $p4 $p5 $p6 $p7 $p8 $p9 $q1 $q2 $q3 $q4 $q5 $q6 $q7 $q8
>             $q9 $r1 $r2 $r3 $r4 $r5 $r6 $r7 $r8 $r9 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $s8 $s9
>             $t1 $t2 $t3 $t4 $t5 $t6 $t7 $t8 $t9 $u1 $u2 $u3 $u4 $u5 $u6 $u7 $u8 $u9 $v1
>             $v2 $v3 $v4 $v5 $v6 $v7 $v8 $v9 $w1 $w2 $w3 $w4 $w5 $w6 $w7 $w8 $w9 $x1 $x2
>             $x3 $x4 $x5 $x6 $x7 $x8 $x9 $y1 $y2 $y3 $y4 $y5 $y6 $y7 $y8 $y9 $z1 $z2 $z3
>             $z4 $z5 $z6 $z7 $z8 $z9
>
>             (start your comparison at $b5)
>
>             So in one axis Pharo has improved Transcript, but we didn't notice the
>             significance of the use case we lost.
>
>             cheers -ben
> 
> 
> Please take a good look at Cuis' Transcript and consider using it.
> 
> By default, the display is updated immediately, but without calling Morphic, it can even work with no UI framework at all. It does updates faster than Squeak or Visualworks:
> 
>         Time millisecondsToRun: [ 1000 timesRepeat:  [ Transcript show: 'x' ] ]. 763.
> 
> But if you want minimum overhead without immediate feedback:
> 
>         Time millisecondsToRun: [ Transcript showOnDisplay: false. 1000 timesRepeat:  [ Transcript show: 'x' ]. Transcript showOnDisplay: true ]. 1.
>         "As fast as Pharo"
> 
> It is also thread safe, and for Ben's example:
> 
> Transcript clear.
> [
>         $a asciiValue to: $z asciiValue do: [ :c |
>                 [ 1 to: 9 do: [ :i | Transcript show: c asCharacter printString , i printString , ' ' ] ] forkAt: 40
>         ].
> ] forkAt: 41
> 
> it gives the same result as Pharo.
> 
> The fact that the updates are not bound to Morphic also means that it is possible to do #show: deep in Morphic logic, without causing infinite loops or recursions, and get immediate feedback. It has
> proved to be a useful aid in debugging Morphic code.
> 
> Cheers,
> Juan Vuletich
> 
> 
> 
> 
> 
> --
> best,Eliot
> 
>