Hi, all! Today I committed a change to Npgsql which will improve connection pool performance. This change was motivated by Andrew's bug report where he noticed that a lot of threads were waiting to get a new connection from pool. In order to keep consistence of the pool, Npgsql has to lock access to it. Andrew's problem appeared in a busy server where a lot of threads were trying to get a new connection from the pool. They had to wait in line. And obviously this isn't good. The current implementation of Npgsql creates a big lock surrounding all the code needed to work with the pool and more! As Andrew noticed in his bug report, I/O operations were being done inside this lock which was contributing to more delays to get a connection from the pool. So, to fix that, I rewrote connection pool logic to remove this big lock and break it down to smaller ones only when really needed. All the I/O operations were left out of the locks , this way, other threads