I hadn’t used this specific solution, but any self-hosted analytics in general should be considered potentially huge resource hog:
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every async action in WordPress is effectively another WP core load, so if tracking code makes even one additional async request to back-end it effectively doubles the load;
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stat logging by nature cannot be cached;
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stat logging by nature needs database writes, which are much more performance-hungry than reads.
Hosted analytics solution are popular exactly because analytics comes with performance challenges.