Complex sentence: The author of "The Big Sleep", Raymond Chandler, claimed that Martha Vickers gave an incredible performance as Carmen Sternwood, so much so that she completely overshadowed Lauren Bacall in her scenes.
Split into simpler sentences: The author of The Big Sleep, Raymond Chandler, claimed that Martha Vickers gave an incredible performance as Carmen Sternwood. So much so that she completely overshadowed Lauren Bacall in her scenes.