If your displays have low FPS or seem to be lagging/stuttering, there are a few ways to troubleshoot this.
If you have 'USE DISPLAY SAFE MODE' and/or 'FORCE SAFE MODE CPU RENDERING' selected, uncheck both of these options (note you will need to restart MSFS for this to take effect).
If you still have stuttering or low FPS displays, or other display issues after this - please contact support with your logs attached.