There were two important blog posts I came across yesterday that detail similarly related problems in ColdFusion 8. Both issues revolve around changes to the JDBC drivers in ColdFusion 8 and they're both essentially transparent issues (unless your running SeeFusion.)
The first issue relates to a new feature in the datasource configuration called the "Validation Query." ColdFusion 8 introduced the ability to define a query that run each time a connection to a DSN is reused after a period of inactivity. This is useful in cases where the CF server might lose connection to the database server due to network issues.
As Daryl Banttari of Webapper reported yesterday, the problem is there's a bug in the Admin API that causes the "Validation Query" for each DSN it touches to be set to the value of "0". This causes ColdFusion to silently through a java.sql.SQLException each time the validation query is executed. Since this is a silent exception, you have no idea it's happening.
This is actually old news—but I thought it was important to be reminded of it. Last year Yahoo's UI blog posted some findings on user browser cache usage. Here's what they found:
40-60% of Yahoo!’s users have an empty cache experience and ~20% of all page views are done with an empty cache. To my knowledge, there’s no other research that shows this kind of information. And I don’t know about you, but these results came to us as a big surprise. It says that even if your assets are optimized for maximum caching, there are a significant number of users that will always have an empty cache. This goes back to the earlier point that reducing the number of HTTP requests has the biggest impact on reducing response time. The percentage of users with an empty cache for different web pages may vary, especially for pages with a high number of active (daily) users. However, we found in our study that regardless of usage patterns, the percentage of page views with an empty cache is always ~20%.
I definitely recommend reading the whole post as there's lots of good information on optimizing your site for performance. This article is just one posting in a series of posts on how to improve your site's HTTP performance.