peaker

Short definition from Wiktionary

Noun

1. 1
   That which reaches or forms a peak.
2. 2
   One whose behaviour or performance reaches a maximum (of something) at a particular time.
3. 3
   A power station that provides energy supply only during peak usage periods.
4. 4
   One who climbs to the peak of one or more mountains.
5. 5
   One who is open to peak experiences.