Started seeing longer delays here doing boolean operations and the model switching to wireframe within a shaded viewport. Moving the model or switching viewport normally returns model to shaded view. This problem appears to me as getting worse as it used to be an occasional glitch but now far more regular.
Probably related to this bug, which looks like it may not be fixed for the first release version. --Mitch
Cheers Mitch I tried to see if there was a relevant fault. No worries I can work with it till we have a fix.