Optimization: don't add txn back to mempool after 10 invalidates

src/validation.cpp

@@ -2797,6 +2797,7 @@ bool CChainState::InvalidateBlock(CValidationState& state, const CChainParams& c
 {
  CBlockIndex* to_mark_failed = pindex;
  bool pindex_was_in_chain = false;
+ int disconnected = 0;
 
  // Disconnect (descendants of) pindex, and mark them invalid.
  while (true) {
@@ -2816,8 +2817,10 @@ bool CChainState::InvalidateBlock(CValidationState& state, const CChainParams& c
  bool ret = DisconnectTip(state, chainparams, &disconnectpool);
  // DisconnectTip will add transactions to disconnectpool.
  // Adjust the mempool to be consistent with the new tip, adding
- // transactions back to the mempool if disconnecting was succesful.
- UpdateMempoolForReorg(disconnectpool, /* fAddToMempool = */ ret);
+ // transactions back to the mempool if disconnecting was succesful,
+ // and we're not doing a very deep invalidation (in which case
+ // keeping the mempool up to date is probably futile anyway).
+ UpdateMempoolForReorg(disconnectpool, /* fAddToMempool = */ (++disconnected <= 10) && ret);
  if (!ret) return false;
  assert(invalid_walk_tip->pprev == chainActive.Tip());