Take the 2-minute tour ×  I'm waiting for Excel to finish a
recalculation and I notice that the CPU usage as reported by
Task Manager occasionally spikes to 51% or 52% on a Pentium 4
with hyper-threading. How is a single-threaded application like
Excel 2003 doing this?  Is it just a rounding/estimation error
on the part of Task Manager? Or is it something to do with HT
allocation i.e. I wouldn't see this happening on a genuine dual-
core or dual-CPU machine?  share|improve this question  3
Answers 3  up vote 6 down vote accepted  I would be surprised if
Excel 2003 is single threaded. It's likely to have at least a UI
thread and a worker thread. Does the UI repaint while the
calculation is going on? If so, Excel is not single-threaded.
share|improve this answer Exactly, it's most likely from a
repaint, or an input thread. Excel 2003 is not "multi-threaded"
in its calculations, but that doesn't mean that the whole
program run on a single thread, of course. –  Gnoupi Mar 25 '10
at 16:50 Rather than arguing about