Hi, @mpheath and All, Ah… I understand. Thus, I’ve decided to conduct a second round of tests. This time : The files New_LF_ANSI.txt and New_CRLF_UTF-8.txt were copied from ORG_LF_ANSI.txt as Regex_LF_ANSI.txt and Regex_CRLF_UTF-8.txt The files Lua_LF_ANSI.txt and Lua_CRLF_UTF-8.txt were copied from ORG_LF_ANSI.txt as Lua_2_LF_ANSI.txt and Lua_2_CRLF_UTF-8.txt Then, I stopped and restarted N++ : thus, no more change history feature ! Finally, regarding these new created files : I ran the regex replacement, followed by a Trim trailing Space operation, on files Regex_LF_ANSI.txt and Regex_CRLF_UTF-8.txt I ran your Lua script on files Lua_2_LF_ANSI.txt and Lua_2_CRLF_UTF-8.txt So, these four files showed an orange change history color. As you can see on the screenshots, the regex process acted on all lines, but some empty line endings, and your lua script just acted on lines which need wrapping ! Regex process : [image: 1793185055863-2227cacc-b95f-4715-9de6-41295fb2754d-image.jpeg] Lua process : [image: 1793185088657-7b25d2ab-cc71-4e82-9fe3-dc3c4f3cd4fa-image.jpeg] However, the comparisons between the regex process and the Lua process shows the same number of differences ( 3 for ANSI files and 5 for UTF-8 files ) Between ANSI files : [image: 1793185122897-7299ef9e-d2d0-46f5-9d1c-a9a4a69473a4-image.jpeg] [image: 1793185134970-7e206be6-1745-46b2-9751-5fdd94e5a2a6-image.jpeg] Between UTF-8 files [image: 1793185153982-bd94b573-9462-4640-99f2-ed0ecbec9ced-image.jpeg] [image: 1793185170805-785051c7-9e8b-476c-8024-9cb249e18ded-image.jpeg] Best Regards, guy038

Hello, @thomas-knoefel and All, Indeed, changing the line : LoadThreads="auto" into this one : LoadThreads=0 within the MultiReplace.ini file, the same list of files were found in 2 m ( instead of 1 m 13 s ) Thus, I decided of an experiment, changing, on purpose, the LoadThreads line to : LoadThreads=8 After restarting my computer and doing the test, the execution time was, this time, 1 m 28 s. However, verifying within the MultiReplace.ini file, I saw the line : LoadThreads="0" Is this the expected behavior, with the number 0 as a string ? Best Regards, guy038