### Describe the issue

Restarting bitcoin, mempool starts filling from scratch.

### Can you reliably reproduce the issue?
#### If so, please list the steps to reproduce below:
1. Wait for mempool to reach for example 3000 transactions
2. Restart bitcoin
3. Watch mempool filling slowly from scratch

### Expected behaviour
Mempool would already contain ~3000 TX on startup

### Actual behaviour
It starts at 0 and fills up slowly with a few per second.

### Screenshots.
http://imgur.com/a/or82d

### What version of bitcoin-core are you using?
Windows x64 0.14rc1 binary from https://bitcoin.org/bin/bitcoin-core-0.14.0/test.rc1/


### Any extra information that might be useful in the debugging process.
I may not be aware of how the mempool.dat thing works and there could just be a misunderstanding.

if (!CheckSequenceLocks(tx, STANDARD_LOCKTIME_VERIFY_FLAGS, &lp))
            return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
        }
        
        if (fRequireStandard && !AreInputsStandard(tx, view))
            return state.Invalid(false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
        
        if (tx.HasWitness() && fRequireStandard && !IsWitnessStandard(tx, view))
            return state.DoS(0, false, REJECT_NONSTANDARD, "bad-witness-nonstandard", true);
        int64_t nSigOpsCost = GetTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
        CAmount nValueOut = tx.GetValueOut();
        CAmount nFees = nValueIn-nValueOut;
        
        CAmount nModifiedFees = nFees;
        double nPriorityDummy = 0;
        pool.ApplyDeltas(hash, nPriorityDummy, nModifiedFees);
        CAmount inChainInputValue;
        double dPriority = view.GetPriority(tx, chainActive.Height(), inChainInputValue);
        
        
        bool fSpendsCoinbase = false;
        BOOST_FOREACH(const CTxIn &txin, tx.vin) {
            const CCoins *coins = view.AccessCoins(txin.prevout.hash);
            if (coins->IsCoinBase()) {
                fSpendsCoinbase = true;