https://github.com/wiredtiger/wiredtiger/blob/42eec1beb18b2e7f0cd7ec7ffeeca58500d14e1e/src/include/cursor_inline.h#L484-L488

The comment says that it isn't needed, and after seeing it hot in a profile I tried commenting out the memset. In one workload that is dominated by time spent calling cursor->next(), that resulting in a 5% speedup. We should decide whether it is actually unnecessary, and if so, remove it. It may be the case that only a subset of the fields need to be initialized, in which case, it would probably be better to only initialized those fields.