Hi,
MonetDB has great response times for the queries I have been running, but once I start inserting data to the table and concurrently running the queries, the queries slow down.  To give you concrete numbers,  I am initializing the database with 8 million records.  I then run random aggregation queries repeatedly.  Before I insert additional data the max query time is 0.3 seconds.  If I then insert 10 rows the queries slow to a max of 1.5s.  The only solution I have to getting the queries to resume their original speed is to drop the data and reload the 8 millions rows into the table.  I have also noticed that if I run my inserts while I am not concurrently making queries to the database, I don't run into the slowness, and the queries keep their 0.3s response time.  Has anyone else encountered this problem before?  Is there a way around it?  I have also tried using the copy command instead of inserts but get the same result.  
Thanks,
Bennett