After looking through the new 1.35/1.36 threading library (with a lot of nice changes), I am wondering why the decision to tie it to boost::date_time was made? I love date_time as a library, but I believe it's is too large and cumbersome to be tied to a core threading library. It pulls in an excessively large include tree whenever I want to use a mutex or conditional variable. The call tree for doing simple comparisons and calculations at second to nanosecond scales is also excessive. There will always be unnecessary converting from seconds and nanoseconds, into the date_time's internal date + ticks format, and back to seconds and nanoseconds. A more fully realized 'xtime' with functions for easy conversion to/from date_time in an optional header would be a much better approach in my opinion. The C++0x draft standard looks like it uses a lean 'system_time' class which is a small subset of date_time. Regards, Ross