Thanks Gustaf, it's all starting to make more sense now. I can see that my approach was quite naive. Very interesting that ad_conn is the slowest part.
The performance issue that our client reported, that was resolved by switching on PerformanceModeP, was a page that had a lot of Javascript that made large numbers of AJAX calls (each to the same URL). This page was very slow to load (up to 4 minutes), and after switching on the parameter, it loaded in less than 10 seconds. However, I have just learned from another developer that actually there was a bug in that page that caused a multiplier effect in the number of AJAX calls, so that e.g. instead of 4 or 5 calls, there were 100s. This has now been fixed, so probably PerformanceModeP will no longer have the same strong effect, but still it makes an interesting case for the benefits of PerformanceModeP.
Of course, the downside to PerformanceModeP seems to be its interaction with this "wizard" tool. It is natural for people to wish for the optimum performance, but not at a price to functionality.
thanks again for the help
Brian
