--- a/src/main.cpp
+++ b/src/main.cpp
@@ -691,7 +691,13 @@
 
     if (fCheckInputs)
     {
-        CCoinsViewCache &view = *pcoinsTip;
+        CCoinsView dummy;
+        CCoinsViewCache view(dummy);
+
+        {
+        LOCK(cs);
+        CCoinsViewMemPool viewMemPool(*pcoinsTip, *this);
+        view.SetBackend(viewMemPool);
 
         // do we already have it?
         if (view.HaveCoins(hash))
@@ -711,6 +717,13 @@
         // are the actual inputs available?
         if (!tx.HaveInputs(view))
             return error("CTxMemPool::accept() : inputs already spent");
+ 
+        // Bring the best block into scope
+        view.GetBestBlock();
+
+        // we have all inputs cached now, so switch back to dummy, so we don't need to keep lock on mempool
+        view.SetBackend(dummy);
+        }
 
         // Check for non-standard pay-to-script-hash in inputs
         if (!tx.AreInputsStandard(view) && !fTestNet)
@@ -741,7 +754,6 @@
             int64 nNow = GetTime();
 
             {
-                LOCK(cs);
                 // Use an exponentially decaying ~10-minute window:
                 dFreeCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
                 nLastTime = nNow;