Comment 15 for bug 1920190

@manu
So actually pdftoraster takes significant time and uses significant ram while processing. But it is using way too much in your case. This is because pdftoraster comes with extended features. Whereas gstoraster is quite fast and it also does not hog this much of memory. Although CPU utilization is high in it too.

In the error_log I can see that pdftoraster exited without errors so in my opinion your system might not have some of the crucial dependencies which specifically pdftoraster requires to do the job efficiently. I am naming some of them here. Please check if your system has these libraries or not. Also try to run pdftoraster after installing these libraries and see if there are any improvements.
1. poppler-cpp
2. poppler-utils
3. liblcms2
4. freetype
5. fontconfig
6.libjpeg
7. libtiff
8. zlib
9. libpng