Pieter, You are correct, it looks to be a problem with memory transfer speeds with the implementation of VESA on the display controller I'm using. On the other had TextDocs spends far less time in Display but is far more consistent with adding characters in the middle of the texts due to it's different architecture. Solution, either use a supported display card or use TextDocs. For now I'll use TextDocs. Testing methodology follows: (KeyTest.Mod is included at the end of the message). Edit.Open "", place the caret in the resulting window and run Configuration.DoCommands StatProf.Start KeyTest.Do StatProf.Stop ~ Move the caret to the beginning of the third line and run Configuration.DoCommands again. In the first run with Edit it inserts 6721 characters and in the second only 92, quite a difference. Here's the results with Edit, Script and TextDocs Legend (all time in mS). (The timings varied from run to run but these are typical). characters, total, time in Displays, Get, Set (the last two get and set are SYSTEM.MOVE instructions in the procedure Displays.Transfer CASE op OF get and set... in the VESA display module) Edit 6721, 20135mS, 14142, 11696, 1715 92, 20038mS, 19904, 17219, 2616 Script 829 20020mS, 18600, 120, 17402 3501 200216mS, 13624, 6130, 4350 TextDocs 4902, 20010mS, 10525, 3146, 5260 3431, 20117mS, 11570, 3684, 4828 MODULE KeyTest; IMPORT Display, Oberon, Texts; VAR W: Texts.Writer; PROCEDURE Do*; VAR M: Oberon.InputMsg; t: LONGINT; ch: CHAR; i: LONGINT; BEGIN t := Oberon.Time(); i := 0; REPEAT M.F := NIL; M.id := Oberon.consume; M.fnt := Oberon.CurFnt; M.col := Oberon.CurCol; M.voff := Oberon.CurOff; IF (i MOD 70) = 0 THEN M.ch := 0DX ELSE M.ch := "a" END; Display.Broadcast(M); INC(i); UNTIL Oberon.Time() > t + 10000; Texts.WriteInt(W, i, 10); Texts.WriteLn(W); Texts.Append(Oberon.Log, W.buf); END Do; BEGIN Texts.OpenWriter(W); END KeyTest. KeyTest.Do System.Free KeyTest ~ Profiler.Profile KeyTest.Do ~ Configuration.DoCommands StatProf.Start KeyTest.Do StatProf.Stop ~