Thank you!
Looking at just the “create plot” messages in the file, I see this:
    create plot   - file   : Total: 4.375 sec, Find-   809 ms, Read-1.173 sec, Ctx:WebPlot-lsst--1
    create plot   - file   : Total: 1.914 sec, Find- 1.67 sec, Read-     1 ms, Ctx:WebPlot-lsst--2
    create plot   - file   : Total: 1.223 sec, Find-   559 ms, Read-     0 ms, Ctx:WebPlot-lsst--3
    create plot   - file   : Total: 1.219 sec, Find-   673 ms, Read-     0 ms, Ctx:WebPlot-lsst--4
    create plot   - file   : Total: 1.183 sec, Find-   622 ms, Read-     1 ms, Ctx:WebPlot-lsst--5
    create plot   - file   : Total: 1.168 sec, Find-   521 ms, Read-     0 ms, Ctx:WebPlot-lsst--6
    create plot   - file   : Total: 1.509 sec, Find-   534 ms, Read-     1 ms, Ctx:WebPlot-lsst--7
    create plot   - file   : Total: 1.615 sec, Find-   758 ms, Read-     1 ms, Ctx:WebPlot-lsst--8
    create plot   - file   : Total: 1.80 sec, Find-   630 ms, Read-     0 ms, Ctx:WebPlot-lsst--9
    create plot   - file   : Total: 1.705 sec, Find-   875 ms, Read-     0 ms, Ctx:WebPlot-lsst--10
    create plot   - file   : Total: 1.190 sec, Find-   594 ms, Read-     1 ms, Ctx:WebPlot-lsst--11
    create plot   - file   : Total: 1.255 sec, Find-   553 ms, Read-     0 ms, Ctx:WebPlot-lsst--12
    create plot   - file   : Total: 1.403 sec, Find-   597 ms, Read-     0 ms, Ctx:WebPlot-lsst--13
    create plot   - file   : Total: 1.498 sec, Find-   659 ms, Read-     1 ms, Ctx:WebPlot-lsst--14
    create plot   - file   : Total: 1.303 sec, Find-   710 ms, Read-     0 ms, Ctx:WebPlot-lsst--15
    create plot   - file   : Total: 1.117 sec, Find-   551 ms, Read-     1 ms, Ctx:WebPlot-lsst--16
    create plot   - file   : Total: 2.116 sec, Find-   588 ms, Read-   780 ms, Ctx:WebPlot-lsst--17
    create plot   - file   : Total: 1.23 sec, Find-   584 ms, Read-     1 ms, Ctx:WebPlot-lsst--18
    create plot   - file   : Total: 954 ms, Find-   470 ms, Read-     0 ms, Ctx:WebPlot-lsst--19
    create plot   - file   : Total: 20.46 sec, Find-19.76 sec, Read-     1 ms, Ctx:WebPlot-lsst--20
    create plot   - file   : Total: 1.84 sec, Find-   545 ms, Read-     0 ms, Ctx:WebPlot-lsst--21
    create plot   - file   : Total: 11.338 sec, Find-10.379 sec, Read-     0 ms, Ctx:WebPlot-lsst--22
    create plot   - file   : Total: 824 ms, Find-   396 ms, Read-     0 ms, Ctx:WebPlot-lsst--23
    create plot   - file   : Total: 832 ms, Find-   376 ms, Read-     0 ms, Ctx:WebPlot-lsst--24
    create plot   - file   : Total: 829 ms, Find-   335 ms, Read-     0 ms, Ctx:WebPlot-lsst--25
    create plot   - file   : Total: 924 ms, Find-   442 ms, Read-     1 ms, Ctx:WebPlot-lsst--26
    create plot   - file   : Total: 1.93 sec, Find-   631 ms, Read-     0 ms, Ctx:WebPlot-lsst--27
    create plot   - file   : Total: 922 ms, Find-   372 ms, Read-     0 ms, Ctx:WebPlot-lsst--28
    create plot   - file   : Total: 1.208 sec, Find-   619 ms, Read-     0 ms, Ctx:WebPlot-lsst--29
    create plot   - file   : Total: 786 ms, Find-   329 ms, Read-     0 ms, Ctx:WebPlot-lsst--30
I notice that there are a couple of cases of very long times (11 and 20 s), which seem to arise from the “Find” time.
The first “create plot” has an unusually large value of (total - find - read).  I’ll let @tatianag see if she can help decode this further.