Complex sentence: Microsoft lagged behind, lacking a dedicated JavaScript engine and being the slowest of the major browsers, although by mid- 2010 they held out the carrot of Chakra in then unreleased Internet Explorer 9.
Split into simpler sentences: Microsoft lagged behind, lacking a dedicated JavaScript engine and being the slowest of the major browsers. Although by mid- 2010, Microsoft held out the carrot of Chakra in then unreleased Internet Explorer 9.