Fast key value storage for application file format

I want to implement file format of my application as key-value storage. I am looking at SQLite but consider it slightly heavy-weight and a little bit slow for my tasks.

In my app i will have about 50k-100k values at max. Most of them will be below 1K size and 20% will have size of about 5-15K

I have such requirements:

1. Stable cross-platform file format


2. Good perfomance (faster than SQLite)


3. Good stability on Windows and Linux


4. Auto compact option


5. Viewer application


6. Simultaneous reading from several processes

I looked at LevelDB and LMDB. Both of them have very impressive perfomance but lacks stability on Windows.

What would you recomment to choose?