Kerbal Space Program

A Spaceplane performs better after the first launch than after quickload or "revert to launch"

Steps to reproduce:
1. launch the attached craft (Jool 5 SSTO) to the runway
2. F5 (Quicksave)
3. Full throttle, SAS on
4. note the speed at end of runway (~160m/s)
5. Retract gear
6. don't touch the controls
7. note maximum speed (~375m/s)
8. F9 or Revert to Launch
10. Repeat from step 3

I just hit 150m/s at the end of the runway and a maximum of 324m/s at sea-level after the quickload
I swapped the rapier engines with the Whiplash and the Panther and got the same results. The craft always performs worse after the first Quickload or revert.
I am unable to get the "Jool 5 SSTO" to orbit after a quickload but it works after the initial lunch of the vessel.