Loop+ bring you a Cubase Vocal time stretching tutorial from the Point Blank vault presented by tutor Danny J Lewis (Defected, Enzyme Black).  This video looks in detail at the various algorithms and customisable time stretching parameters available in Cubase 6.
 

About time stretch (Legacy Cubase 6)

In Cubase, time stretching and pitch shifting algorithms are used for numerous operations (e.g. the Time Stretch and Pitch Shift offline processes, in the Sample Editor, or by the Flatten function).  Time modes include - the élastique algorithm is suited for both polyphonic and monophonic material, three types of algorithm are available, plus the MPEX mode which is an alternative high-quality algorithm.

Limitations

Applying time stretching or pitch shifting to audio material can lead to a degradation in audio quality and to audible artefacts. The result depends on many factors, such as the source material, the particular stretch and pitch operations applied, and the selected audio algorithm preset.  As a rule of thumb, smaller changes in pitch or duration cause less degradation.