Thanks for the detailed report. Let me reply one-by-one.

> 1) history plots on 12 hrs, 24 hrs tend to hang with "page not responsive". most plots have 16-20 variables, 
> which are recorded at 1/sec interval. (yes, we must see all the variables at the same time and yes, we want to 
> record them with fine granularity).

Attached is a similar plot. 8 values recorded every second, displayed for 24h. The backend is actually a Raspberry Pi! I see no issues there. Do you have 
the current history version which does the re-binning? Actually the plot below is still without rebinding (see the "1" at the top right), and it contains ~72000 points x 8. The browser does not have any issue 
with it.

Stefan