irksome vs laborious

irksome

adj
  • Marked by irritation or annoyance; disagreeable; troublesome by reason of long continuance or repetition 

laborious

adj
  • Mentally difficult; painstaking. 

  • Industrious. 

  • Requiring much physical effort; toilsome. 

How often have the words irksome and laborious occurred in a corpus of books? (source: Google Ngram Viewer )