Update.
After a lot of testing, found out that VSYNC on (in XP11) was causing this lag.
TBM is now rock solid and fluid.
I just finished a test flight KVUO / KSEA in a manually generated heavy thunderstorm/rain/wind and it all went smoothly. Landed safely too on 34C.
But I must add: that radar is the best I've seen in flight simming. There was a huge cell ahead, selected a bearing and avoided it. Nexrad is a nice addition also.
Brilliant piece of software gents,
Cheers