Even lighter than SQLite
Are you sure that you have obtained the maximum speed available from SQLITE? Out of the box, SQLITE is extremely safe, but quite slow. If you know what you are doing, and are willing to risk db corruption on a disk crash, then there are several optimizations you can do that provide spectacular speed improvements.
In particular:
- Switch off synchronization
- Group writes into transactions
- Index tables
- Use database in memory
If you have not explored all of these, then you are likely running many times slower than you might.
I'm not sure you'll manage to find anything with better performances than SQL. Especially if you want operations like JOINs... Is SQLite speed really a problem? For simple requests it's usually faster than any full SGDB.Don't you have an index problem?
About size, it's not event 1Meg extra in the binary file, so I'm a bit suprised it's a problem.
You can look at Berkeley DB which has to be probably the fastest DB available, but it's mostly only key->value database.
If you really need higher speed consider loading the whole database in memory (using SQLite again).