Hi,
Were you observing any issues in TestComplete's performance before when you were using any other scripting languages within your other projects?
Do you have any other applications you have open at the time while you are using this python based TC project?
Is the performance related issue only when you stop recording when TC generates the KDT and also after the test runs when it generates the log results?
Have you tried going through the various performance enhancing topic docs to see if these settings are being followed? https://support.smartbear.com/testcomplete/docs/working-with/best-practices/performance-tips.html
https://support.smartbear.com/articles/testcomplete/test-playback-performance-tips/
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and finally, if the performance issue is causing severe delays in your workflow, then please submit a support ticket, where you can use the report generator utility and upload the details of your machine; and we can look into why that is happening.