Cache should be on your internal drive or on a separate drive from everything else, and should be the same place for all caches in adobe for linking to work well. You need a Huge SSD for adobe install. I suggest a fast HDD instead, and set cache internal, with all previews (audio and video in same place) and project files in same place (proxies and project not full prores files only proxies), and keep full formats (AVC or prores) on a fast ESATA, Firewire, USB3 or thunderbolt RAID. This will maximize performance.
Works for me with 2k files on a 2009 mbp with 2.16ghz core2duo, 4gbram, 256mb gfx.