Yes, Post Pay Counter supports caching and is compatible with WordPress caching plugins.
Post Pay Counter mostly implements caching for post stats, plugin settings, user settings and active payment criteria.
Since Post Pay Counter version 2.745 (May 2017), server side caching improves stats performance significantly.
On our tests, with several payment criteria active (words, visits, Facebook shares, comments), we manage to load around 10k posts in under 5 seconds on an average VPS. Un-cached stats may take up to 15 seconds to show up though, so the performance boost is clear.