Below I am using v2.32 of KeePass and v2.0.2 for KeePassX, and I am using Linux.
I was messing around with the number of transform rounds and noticed when choosing one second delay in KeePassX (this is called benchmark on KeePassX) gives 21760000 rounds and KeePass gives 522174. KeePassX opens both files very quickly, taking about a second on the 21760000 rounds one, while KeePass opens the 21760000 round file in around 43 seconds. To rub salt in the wound, Keepass2Android opens the 21760000 file in around 4 seconds, and the other pretty close to instantly.
What is causing such a large difference in performance between the key transformation rounds for KeePass and KeePassX?
It appears KeePass is doing something wrong, at least on the Linux version. Also note 21760000/43 is approximately 522174. I am somewhat worried that KeePass could be giving a false sense of security, since it appears an attacker could potentially be more far efficient at brute forcing than KeePass lets on.
(I know KeePass and KeePassX are not exactly related to each other)
Update: I tested on my laptop at work (which is older, and the hardware isn't nearly as good), with more up to dated software and KeePass v2.34 took about 25 seconds and KeePassX(v2.0.3) took about 7 seconds. When I get a chance I will update software on my home desktop, but it seems the question is still valid since those are the most up to date software and that is still a pretty big difference.