When using the Odoo 7 web interface to build a quotation, once the quotation includes 50+ line items, clicking the link to "Add an item" yields a red "Loading" message which flashes for 20+ seconds.

The behavior is not specific to any particular quotation.

Quotations with only a few line items respond quickly.

Viewing the web traffic on the client shows a request approximately every 100ms to /web/dataset/call_kw which continues for as long as the red "Loading" message is flashing.

Setting log_min_duration_statement on the PostgreSQL server does not show any queries taking longer than 20ms with most queries responding in <1ms.

The server is very lightly loaded. During the request, top shows the server load average <0.1, one Python process using about 10-20% CPU, several PostgreSQL processes each using 2-5% CPU, approximately 2GB RAM in use, another 2GB RAM available. No disk partitions are anywhere close to being full. There are no other services running on this server.

There are no interesting logs.