Hard drive reading slowly?

The two are not directly comparable. The PC games typically have higher resolution models (better graphics) and then there is os overhead like Johnka said. You can try something like crystal disk mark to benchmark your pc drive and do a google search to compare figures to other people bench marking a drive with similar specs. At the very least you need to compare to drives of similar speed. almost all normal size hard drives are 7200 rpm. Alternately, you can run SMART tests and other drive diagnostics. Seagate SeaTools is a free diagnostics utilitay that works on almost any drive.

Perhaps there is not enough memory allocated to the application, impossible to say without more detail about PC and the software hardware it is running.

PC is doing other things as well as loading game.

They are not the same. You're comparing apples to oranges.