SQLite index very slow

[tskisner]

The SQLite index is so slow that it is a blocking factor. Looking through the code, there are several key mistakes:

1. prepared statements are re-created every transaction, rather than creating once and binding values.
2. When doing a single meta-data operation (adding or deleting one object), then it is fine to make that a single transaction. When replaying an long list of operations, these should be batched into a single transaction.

[tskisner]

This problem was addressed mainly by 481fc62, and also the following commit which used PRAGMA options to sqlite to configure it for better performance.