How to reproduce it:
1. Open the attached project "1314181.zip"
2. Load the "TestScene" Scene
3. Set Profile Analyzer's Mode to 'Compare' and click on 'Open Profiler Window' in the Profile Analyzer window (Menu > Window > Analysis > Profile Analyzer)
4. Uncheck the 'Use Render Graph' checkbox in the HDRP Default Settings (Menu > Edit > Project Settings > HDRP Default Settings)
5. Enter the Play Mode
6. Wait few seconds, and in the Profile Analyzer window click the blue 'Pull Data' button
7. Leave the Play Mode
8. Check the 'Use Render Graph' checkbox in the HDRP Default Settings
9. Enter the Play Mode
10. Wait few seconds, and in the Profile Analyzer window click the red 'Pull Data' button
11. In the Profiler Analyzer window in the 'Top 10 markers on median frames' select 'DoRenderLoop_Internal()' marker
12. Compare CPU usage in Marker Summary section in Profiler Analyzer

Expected result: It takes around the same time (difference ~1ms) to render the Scene when Render Graph is used and it is not used
Actual result: It takes more time (4 - 5ms) to render a Scene when the Render Graph is used

Reproducible with: 10.1.0, 10.2.0 (2020.2.0b12), 10.3.2 (2020.2.3f1), 10.4.0 (2020.3.4f1)
Could not test with: 7.5.3 (2019.4.24f1) (Render Graph is not introduced yet), 11.0.0 (2021.1.0b6), 12.0.0 (2021.2.0a13) (cannot compare CPU usage due to not existing 'Use Render Graph' option)