With `dolt_transaction_commit=1`, large latency for `START TRANSACTION` and `SET TRANSACTION ISOLATION LEVEL SERIALIZABLE`.

On hosted instance running Dolt `v0.75.9`, seeing unexpectedly large query latency times for what should be almost instant queries:
```
2023-04-06T17:06:37Z DEBUG [conn 1074] Query finished in 1752 ms {connectTime=2023-04-06T16:29:49Z, connectionDb=dolthubapi, query=SET TRANSACTION ISOLATION LEVEL SERIALIZABLE}
```
```
2023-04-06T17:06:37Z DEBUG [conn 1080] Query finished in 1726 ms {connectTime=2023-04-06T16:29:50Z, connectionDb=dolthubapi, query=START TRANSACTION}
```

These times can be as low as < 50ms, or as high as the above.