Page exists cache is written more than needed leading to possibly slow page loads

After more careful investigation, it seems that in the reported stack trace, the affected cache is in fact the document/page cache itself, not the page exists cache. Further, it seems likely that the actual root cause of those timeouts is not write load (write load only makes it visible) but in fact stack overflows that leave locks locked. I've reported XWIKI-23303 for this. Still, it doesn't seem good to write into caches when no invalidation is needed as this could still cause slowness due to locking under high load.