It's very slow to open many BDB tables at the same time. If you are going to use BDB tables, you should not have a very big table cache (like >256) and you should use --no-auto-rehash with the mysql client. We plan to partly fix this in 4.0.
SHOW TABLE STATUS doesn't yet provide that much information for BDB tables.
Optimize performance.
Change to not use page locks at all when we are scanning tables.