使用'Ajax updated'数据集和crossfilter

I have a really large dataset (about 500 000 records...) about the CO2 emission on London that I want to display with maps and charts using crossfilter. For reasons of performance, I want to do queries beforehand by boroughs, so I've done an ajax function that does that dynamically when I click on a borough (just imagine a map of london with borough boundaries where we can click on them). The Ajax code works fine :I have a really large dataset (about 500 000 re