The Slew Rate Limiter section of the Neutron is split up into PORTA TIME and SLEW. 

The PORTA TIME dial adjusts the time it takes for the oscillators to transition between MIDI notes. The higher the setting, the longer it takes. This is also known as the glide.

The SLEW dial is used to limit the rate of change of a signal. For example, Slew can be used to add Portamento to pitch CVs generated from an external sequencer.