Performance issue in 6.0

**Description**

It's reported that the 6.0 version replays much slower than earlier versions.

I guess it's a side-effect of https://github.com/bitshares/bitshares-core/pull/2528 . Need profiling to know more.

**Impacts**
Describe which portion(s) of BitShares Core may be impacted by this bug. Please tick at least one box.
- [ ] API (the application programming interface)
- [ ] Build (the build process or something prior to compiled code)
- [ ] CLI (the command line wallet)
- [ ] Deployment (the deployment process after building such as Docker, Travis, etc.)
- [ ] DEX (the Decentralized EXchange, market engine, etc.)
- [ ] P2P (the peer-to-peer network for transaction/block propagation)
- [x] Performance (system or user efficiency, etc.)
- [ ] Protocol (the blockchain logic, consensus, validation, etc.)
- [ ] Security (the security of system or user data, etc.)
- [ ] UX (the User Experience)
- [ ] Other (please add below)

## CORE TEAM TASK LIST
- [ ] Evaluate / Prioritize Bug Report
- [ ] Refine User Stories / Requirements
- [ ] Define Test Cases
- [ ] Design / Develop Solution
- [ ] Perform QA/Testing
- [ ] Update Documentation

Start by profiling block replay in the 6.0 version and comparing it with an earlier version, with particular attention to the changes in pull request #2528. Identify the regression's bottleneck and verify that replay performance is restored after the fix.

Written by the indexing model from the issue text.