A few zippers have scripting methods included. I don't know them so resort to ugliness.
Copy to compressbigstuff.bat:
Code:
@echo off
for %%i in (*.txt) do if %%~zi GTR 250000000 7za a dummy -tgzip -so %%i > %%~ni%%~xi.gz && 7za t %%~ni%%~xi.gz && if %ERRORLEVEL% EQU 0 erase %%i
Scary but functional. It only compresses 250MB txt files as is. Assumes 7za (
http://www.7-zip.org/) is in your path. (BTW, 7zip is very efficient compared to rar, winzip, etc.)
Change the "(*.txt)" to "*" for everything, or allow passing in your own directory with %1, etc. You could have it follow directories by changing "for" to "for /R", but I wasn't that adventurous. (see "for /?" from the command line)
7zip can be multithreaded if you ask it to be with some compression types. I wouldn't bother forcing multiple instances or it'll be slower from overhead and thrashing, and force file fragmentation.