Ok, find reason. In default project settins is audio bitrate set to 48000. My souncard has 96000. That causes Vegas play clips sicnifically faster. Changed project audio rate to 96000 and clips play in normal speed again.
Isn't this a case where the video was recorded at 60fps with audio. Then when it is imported into a 30fps project you effectively get 50% slow motion video with real time audio being exactly half as long as the video in your clip example.