Try WhySoSlow:
The Download is on
http://www.resplendence.com/downloads
Look under System Monitoring Tools for WhySoSlow 1.0 then click on
Download free home edition
Save the file then right click and Run As Admin. Follow the prompts. Let it run for a minute (watch the Time Running indication at the bottom) then hit Analyze
Then when a new window appears hit Analyze again. Once the report appears scroll down and see if it complains about anything. You can Save the report but it saves as WhySoSlowOutput.htm which the forum won't let you attach. You can either zip it up or rename it to WhySoSlowOutput.txt then attach it.
Do you still get holes in your website? Does it make any difference which browser you use?