The general trick to reduce the time an UltraEdit macro or script takes to complete a task is writing the macro or script to produce as less window updates as possible. This can be achieved usually using regular expression replace all commands to reformat a file with as less window updates as possible.

For small files up to about 20 MB it is even possible to use a script which loads entire file content into memory of JavaScript core on execution of the script, reformat in memory the file content and output the reformatted text back to file with overwriting existing content. This results in just two window updates and in recording just one undo step and is the most efficient method to reformat a file for that reason.

The time a macro or script needs to finish which results in lots of Windows updates can be reduced by using Classic theme of UltraEdit and if possible configure Windows to use also Classic theme (Windows 7). All those graphic effects like shading and color fading take a quite long time to be calculated and finally drawn on screen. In my experience with a macro processing a Windows registry file with more than 100 MB using mainly regular expression replace all commands the difference between Classic theme and the other non Classic themes is about factor 3, i.e. the macro takes three times longer to finish with themes like Slate or Modern Light in comparison to Classic theme. Well, I use a customized Windows 7 Classic desktop theme with having additionally disabled color fading in title bar of windows and use also a customized UltraEdit Classic theme because I like the puristic look and don't need a stylish look. That makes window updates most efficient, not only in UltraEdit, but in all Windows applications not ignoring completely the Windows desktop theme settings. Windows 10 is not used by me at the moment.

The undo recording cannot be disabled with a macro or scripting command. No modifications are recorded for undo feature on using Replace in Files. It is possible to run Replace in Files on just active file. So it would be possible that a macro or script using just Replace All commands executed from top is modified to run just Replace in Files commands on this file for fastest reformatting of the file with just output window updates and without undo records.

That's fine.

The macro command to set caret to a specific column in current line is GotoLine 0 x whereby line number 0 is interpreted as current line and x is the column number with first column in a line having number 1.

It would be also possible to use a Perl regular expression Find like Find MatchCase RegExp "^.{50}\K" to search for exactly 50 characters after start of a line and keep back found string which means nothing is selected and therefore just caret is blinking in line after the first 50 characters. Please note that the Perl regular expression find interprets a horizontal tab character as one character even if the tab takes multiple columns in displayed text depending on tab stop and indent value configured for active file.

BTW: The parameter MatchCase is used although there is no difference between a case-sensitive and a case-insensitive regular expression find with this search string because of case-sensitive finds/replaces are always faster than case-insensitive finds/replaces. That is one more general trick to reduce macro execution time. Finds/replaces should be run case-sensitive wherever possible.