### 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 (pindex->nHeight < chainActive.Height()-nCheckDepth)
            break;
        if (fPruneMode && !(pindex->nStatus & BLOCK_HAVE_DATA)) {
            
            LogPrintf("VerifyDB(): block verification stopping at height %d (pruning, no data)\n", pindex->nHeight);
            break;
        }
        CBlock block;
        
        if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
            return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
        
        if (nCheckLevel >= 1 && !CheckBlock(block, state, chainparams.GetConsensus()))
            return error("%s: *** found bad block at %d, hash=%s (%s)\n", __func__,
                         pindex->nHeight, pindex->GetBlockHash().ToString(), FormatStateMessage(state));
        
        if (nCheckLevel >= 2 && pindex) {
            CBlockUndo undo;
            CDiskBlockPos pos = pindex->GetUndoPos();
            if (!pos.IsNull()) {
                if (!UndoReadFromDisk(undo, pos, pindex->pprev->GetBlockHash()))
                    return error("VerifyDB(): *** found bad undo data at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
            }
        }
        
        if (nCheckLevel >= 3 && pindex == pindexState && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
            bool fClean = true;
            if (!DisconnectBlock(block, state, pindex, coins, &fClean))
                return error("VerifyDB(): *** irrecoverable inconsistency in block data at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
            pindexState = pindex->pprev;