One hour difference in a two hour job? Frightening!

Not directly relevant as I’m using Linux but all my times are within 0.01 hours.

of course, I working on this computer and generating additional workload for CPU and these activities should decrease capacity of ELAPSED TIME of my computer for WCG.
but this does not explain the low utilization of CPU TIME

Elapse time never stops running, but the more outside processes are running on the CPU, the less CPU time will be allocated to BOINC.

As Sgt. Joe said, you should check for software that might be using the CPU outside your normal usage. There could be a Windows process, etc.

For example: for several weeks, the AMD Radeon Software was using 1 full core on my PC, I had to terminate the process after each reboot. Eventually, it fixed itself without my input or updates-

CPU time measures all the time spent actually crunching WCG units. However, WCG only operates in down time, so every time you hit enter, or do some other process, you are no longer in down time, for one or more cores/threads.

Elapsed time includes all suspensions for these other processes. So the harder you work your machine on other purposes, the bigger the disparity between elapsed time and CPU time.

As others have said, check your task manager to see if anything else is taking a significant % of CPU time. Other than what you need for work of course.

Mike