Hi Daniel !
A typical recommandation is a good compromise between the speed and the memory : 4 cores, 16Gb of Ram, and a fast hard disk (SSD) for the working folders (the results and the temp folders).
The report can indeed takes time to be generated when there are lots of violations.
Choosing Word (docx) for the output format is faster than pdf. HTML is even faster than Word, but some people don't like reports in HTML.
Regards,
Alex