I am trying to map over 100k points using Client-side featureLayer. It works very well but fails if graphics are over 60k (Actually start failing from 62432). I also tested with featureReduction enabled but still the same.
You can test by changing the total at: https://jsfiddle.net/aqxk15zu/.
It looks like it's both memory and browser dependent. In Chrome (81.0), I would get a "script error" message above 125380 points. In Firefox (76.0), I would run out of memory somewhere between 400000 and 450000 points. If I put 500000 points, I got a "RangeError: too many arguments provided for a function call" error
Thanks for testing and reply! I just tested on different browsers and got different numbers. Seems like I will have to cluster data by myself before putting into featureLayer to make sure it does not fail.