Not scarey as previous posted. If you have any experience driving it is safe. Tour buses and semi travel both routes.
Relax and enjoy the ride down highway 50 to Sacarmento and on to San Fran. The road is good and yes you are going down hill from Tahoe to Sacramento but it isn't the Rocky Mountains. It is a good two lane.
Just take it at normal speed and enjoy the trip.
Now if you want to go around Lake Tahoe to Reno then west on Interstate 80 it is wider and higher speeds but you also have to go down hill there also.
Either way is good and you shouldn't worry.
Enjoy your trip.