diff --git a/src/chain.h b/src/chain.h
index f1d28a5b58..99b63408f7 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -200,6 +200,7 @@ class CBlockIndex
 
     //! (memory only) Maximum nTime in the chain up to and including this block.
     unsigned int nTimeMax{0};
+    CBlockIndex *lastAlgoBlocks[NUM_ALGOS_IMPL];
 
     CBlockIndex()
     {
@@ -212,6 +213,9 @@ class CBlockIndex
           nBits{block.nBits},
           nNonce{block.nNonce}
     {
+         for (unsigned i = 0; i < NUM_ALGOS_IMPL; i++)
+             lastAlgoBlocks[i] = nullptr;
+         lastAlgoBlocks[GetAlgo()] = this;        
     }
 
     FlatFilePos GetBlockPos() const {
diff --git a/src/pow.cpp b/src/pow.cpp
index 9c178ed422..4a213cfbb7 100644
--- a/src/pow.cpp
+++ b/src/pow.cpp
@@ -200,7 +200,7 @@ unsigned int GetNextWorkRequiredV4(const CBlockIndex* pindexLast, const Consensu
         pindexFirst = pindexFirst->pprev;
     }
 
-    const CBlockIndex* pindexPrevAlgo = GetLastBlockIndexForAlgo(pindexLast, params, algo);
+    const CBlockIndex* pindexPrevAlgo = GetLastBlockIndexForAlgoFast(pindexLast, params, algo);
     if (pindexPrevAlgo == nullptr || pindexFirst == nullptr)
     {
         return InitialDifficulty(params, algo);
@@ -239,6 +239,10 @@ unsigned int GetNextWorkRequiredV4(const CBlockIndex* pindexLast, const Consensu
         {
             bnNew *= (100 + params.nLocalTargetAdjustment);
             bnNew /= 100;
+            if (i % 16 == 0 && bnNew > UintToArith256(params.powLimit)) {
+              bnNew = UintToArith256(params.powLimit);
+              break;
+            }            
         }
     }
 
@@ -343,6 +347,25 @@ const CBlockIndex* GetLastBlockIndexForAlgo(const CBlockIndex* pindex, const Con
     return nullptr;
 }
 
+const CBlockIndex* GetLastBlockIndexForAlgoFast(const CBlockIndex* pindex, const Consensus::Params& params, int algo)
+{
+    for (; pindex; pindex = pindex->lastAlgoBlocks[algo])
+    {
+        if (pindex->GetAlgo() != algo)
+            continue;
+        if (params.fPowAllowMinDifficultyBlocks &&
+            pindex->pprev &&
+            pindex->nTime > pindex->pprev->nTime + params.nTargetSpacing*2)
+        {
+            pindex = pindex->pprev;
+            continue;
+        }
+        return pindex;
+    }
+
+    return nullptr;
+}
+
 uint256 GetPoWAlgoHash(const CBlockHeader& block)
 {
     return block.GetPoWAlgoHash(Params().GetConsensus());
diff --git a/src/pow.h b/src/pow.h
index 0a61af7128..9014311667 100644
--- a/src/pow.h
+++ b/src/pow.h
@@ -26,6 +26,7 @@ unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nF
 /** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
 bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params&);
 const CBlockIndex* GetLastBlockIndexForAlgo(const CBlockIndex* pindex, const Consensus::Params&, int algo);
+const CBlockIndex* GetLastBlockIndexForAlgoFast(const CBlockIndex* pindex, const Consensus::Params&, int algo);
 uint256 GetPoWAlgoHash(const CBlockHeader& block);
 
 #endif // DIGIBYTE_POW_H
diff --git a/src/validation.cpp b/src/validation.cpp
index d6aca6c6e2..696893041e 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3097,6 +3097,13 @@ CBlockIndex* BlockManager::AddToBlockIndex(const CBlockHeader& block)
         pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
         pindexNew->BuildSkip();
     }
+
+    if (pindexNew->pprev) {
+        for (unsigned i = 0; i < NUM_ALGOS_IMPL; i++)
+            pindexNew->lastAlgoBlocks[i] = pindexNew->pprev->lastAlgoBlocks[i];
+        pindexNew->lastAlgoBlocks[pindexNew->GetAlgo()] = pindexNew;
+    }
+
     pindexNew->nTimeMax = (pindexNew->pprev ? std::max(pindexNew->pprev->nTimeMax, pindexNew->nTime) : pindexNew->nTime);
     pindexNew->nChainWork = (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) + GetBlockProof(*pindexNew);
     pindexNew->RaiseValidity(BLOCK_VALID_TREE);
@@ -3889,6 +3896,13 @@ bool BlockManager::LoadBlockIndex(
         }
         if (ShutdownRequested()) return false;
         CBlockIndex* pindex = item.second;
+
+        if (pindex->pprev) {
+            for (unsigned i = 0; i < NUM_ALGOS_IMPL; i++)
+              pindex->lastAlgoBlocks[i] = pindex->pprev->lastAlgoBlocks[i];
+            pindex->lastAlgoBlocks[pindex->GetAlgo()] = pindex;
+        }
+        
         nHeight = pindex-> nHeight;
         pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + GetBlockProof(*pindex);
         pindex->nTimeMax = (pindex->pprev ? std::max(pindex->pprev->nTimeMax, pindex->nTime) : pindex->nTime);