Yes, the reason it takes so long is, the patch has lots of JA files, which need to be decompressed from the patch install file as well from the existing JA files on your PC (to add the new decompressed JA files to these) while installing and then re-compressing these JA files again on your PC after they are installed.
Jes, I know, a pain in the proverbial but if patching is left alone, even after using a long time to do its thing, it should be OK .......eventually.
Most of the time, unless the threaded warning comes up after installing for a long time:
"Can not continue with patch/upgrade" or whatever.
Lennard