ok so I do something like this with a custom script to multiply data
function beforeRender(req, res) {
for (let i = 0; i < 400; i++) {
req.data.Data[0].INC.push(req.data.Data[0].INC[0])
}
}
With 400 more items, it takes 10s to chrome to do the html conversion and produces 146 pages.
With your expected data, 40 000 items, it is 100x more so you expect the result of 14 600 pages?
This will be very hard to optimize to 4min. The majority of the rendering time is used by chrome to do the html->pdf conversion and this is something we have no influence on. You could try to replace the table elements with divs which are typically faster, but you would lose some layout features table provides.
One option is to split the big report to the chunks and do the printing in parallel to employ all the cpu cores, because chrome typically uses just cone core. I uploaded here a demo how it could work, please check it out and let me know if you have some good results with it
https://1drv.ms/u/s!AogtKyPn-GjbhLZ0wLCCU6HHdZAyQw?e=ENQWx6
