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A partial answer.
After some time with WingIDE IDE’s debugger, and some profiling with cProfile, I have located the main CPU hogging issue.
During initial django startup there’s a cascade of imports, in which module validators.py prepares some compiled regular expressions for later use. One in particular, URLValidator.regex, is complicated and also involves five instances of the unicode character set (variable ul). This causes re.compile to perform a large amount of processing, notably in sre_compile.py _optimize_charset() and in large number of calls to the fixup() function.
As it happens, the particular combination of calls and data structure apparently hit a special slowness in WingIDE 6.0b2 debugger. It’s considerably faster in WingIDE 5.1 debugger (though still much slower than when run from command line). Not sure why yet, but Wingware is looking into it.
This doesn’t explain the occasional slowness when launched from the command line on Windows; there’s an outside change this was waiting for a sleeping drive to awaken. Still observing.
