This may be naive but I am unsure how you tell what applications benefit most from single core performance vs multi core performance. I feel like upgrading my server to a processor with higher single core performance will benefit the “snappiness” because the CPU utilization percentage sits at such a low level. But that may not even make sense.
I always recommend OwnCloud. It even has a raw photo viewer plugin and if you know anything about RAW 24 megapixel photos, they are tough to load. But with owncloud a folder full of 30 pictures loads within 10-15 seconds