Do you mean you reference remote images in <img src='your url'/> and then let the chrome to convert to pdf? In this case, jsreport does not influence how these images are loaded and converted. Everything is done by chrome. There is typically no limit on how many images chrome can convert.
Do your images have the final size you want to embed in the pdf? The big images are often causing perf problems.
https://jsreport.net/learn/chrome-pdf#performance-optimization