I can't really remember, but we had tens of millions of files and the directory depth was 2, so there were approx. 80000 files in each directory (we used an md5

I can't really remember, but we had tens of millions of files and the directory depth was 2, so there were approx. 80000 files in each directory (we used an md5 checksum for the directories). And we used ext3. I understand that the speed with large directories was increased in ext4... maybe that was the problem back then.