Hi Paul,
Thanks again for your continued input here...
I've actually designed the test harness so that it does not re-open the project for each test. So for each test run, it opens the project suite before the first test runs, executes all tests within the TFS test plan that I'm running, then closes the project suite upon completion.
I am fairly certain it has at least something to do with the size/number of scripts in the project. The slow test startup also occurs when I run an individual test locally on my machine from within TestComplete, although it isn't near as bad. It is also interesting that the problem doesn't seem to occur if I execute a test directly from the script rather than through the project's test items. Each test has an associated test item in the project, so there are also ~700 test items. I need to execute from the test items though because each test has individual timeout values that I need to utilize.
We have an entire lab of computers, some with antivirus software and some without, but the problem seems to occur despite this.