Hello,
I have the same problem, but not only during the cutscenes or dialogues, but also in a combat. Initially, this issue appear in a dialogue with Liara about prothean, but I performed all solutions that I found on EA forum and this allowed me to move on to the battle, but that's it - now nothing helps.
What have I done so far:
- upgraded graphic drivers (performs a clean installation every time via GrFoce Experience) and all Windows drivers with Windows Update,
- repaired the game in Origin & Steam,
- reinstalled the game,
- switched off V-sync in Nvidia configuration,
- switched off V-sync in ME3,
- uninstalled all programs to monitor GPU & CPU,
- switched off antivirus program.
I attached DxDiag file.