I think 10,000 datapoints is the limit in 2d visualization but even 1000-2000 datapoints is often acceptable limit. It's usually reasonable to reasonable to downsample and decimate data before presenting it. If user zooms into data, it should be handled in some other ways than keeping all data.
But if the library supports zooming, I highly appreciate it if I can just put my 10,000 to 100,000 datapoints into the library, specify a simple filter function (avg, sum, min, max) and let the library pick the points it wants to display at each zoom level.
Beyond ~100,000 datapoints any filtering is likely better done in the database than on the client. For values below that, Javascript is more than capable.
A 100,000 data point file would be about 500kb transfered to the client. This is still a tiny amount of data to play around with in JS. It is possible to build an array of image tiles, and zoom around like google maps. But keeping the image tiles in memory could be worse than just replotting if the plot function is fast and optimized enough.
Thanks!