Thanks for the feedback!
The main reason for this is that I'm using the good and lightweight third party tracking API that FedEx and USPS provide while I'm reading all the information manually from the UPS tracking website. This means that for UPS there's much data to search through for filtering out the relevant information.
Nevertheless by looking into it deeper, I found a major performance issue in a Java component I use for going through all the data and by working around this, my tests showed reduced parse times by 30-60%.
I'll release this in the next update and hope that it will be a noticeable improvement for you.