Multiple download size smaller than individual download

I have the problem that if I select 2 files (total size 4.4GB) and click on the Download button, I only get 366MB down. But if I select the files individual to download, the files do get the right size (3.1GB and 1.3GB). I assume it has to do with memory restrictions (maybe for PHP). Even if i select just one file (3.1GB) and click on the Download button it still only gives me 366MB.

How does the multiple download function work, to combine the files? Would any PHP memory restrictions cause this issue?

I just double checked, and it seems if I select 2 files (4.3GB and 42KB), then click Download, it goes correct. When I only select 1 file (4,3GB) and click Download, it only gives me 366MB.

I am currently running NC 10RC1

Are you using a 32-bit system?

No I only use 64-bit for all my servers.