  The first level trigger of the CMS experiment is comprised of custom
electronics that process data from the electromagnetic and hadron calorimeters
and three technologies of muon detectors in order to select the most
interesting events from LHC collisions, such as those consistent with the
production and decay of the Higgs boson. The rate of events selected by this
Level-1 trigger must be reduced from the beam crossing frequency to no more
than 100 kHz further processing can occur, a major challenge since the LHC
instantaneous luminosity has increased by six orders of magnitude since the
start of operations to more than 6E33 cm-2s-1 today. The performance of the
Level-1 trigger, in terms of rates and efficiencies of the main objects and
trigger algorithms, as measured from LHC proton collisions at 7 and 8 TeV
center-of-mass energies is presented here.
